Below you will find a few quotes from Paul Kane plucked from this thread.
Yes, things have changed. The economy has put the majority of suppliers into a JIT ("just in time") mode. This means that very little inventory is kept on the shelf and parts are fabricated on an as-needed basis. In the case of main caps, the manufacturer may wait until a reasonable quantity justifies the expense of the production run. It's just the reality of the current economical situation and what business must do to maintain liquidity and survive.
I don't need to know from whom you are attempting to get D0VE-A style splayed caps, but there are plenty available if you don't mind using 1025 carbon steel CAT caps. The CAT caps are certainly stronger than any D0VE-A block's cast 4-bolt parallel caps; they will be the strongest part of a production D0VE-A block; they are inexpensive (less than $100), and they are a single piece of billet steel which you will fully machine for the application anyway. We have used them on about 8-9 engines ranging from a 700+ hp naturally aspirated marine engine to a blown 521 monster truck engine. Zero problems.
Generally, they are identical in appearance (<---shape) to the Milodon ductile iron caps except that the CATs are made of steel and are black-oxided instead of gold iridited.
They are advertised as a 17-degree spayed cap. They are a single-register main cap made to be fitted to the D0VE-A blocks specifically, not a double-register cap (a la Blue Thunder) which is meant to have the standard-webbed (non-D0VE) blocks machined to accept the BT cap's outer registers. The thrust bearing register does not need to be machined because the overall thickess of all 3 CAT caps is equal to the OEM SCJ center cap's thrust register thickness (this main cap width is adequate to accommodate all main bearings without any "overhang").
By "fullly machine," I mean that you will need to carefully prepare them as you would any other aftermarket main cap conversion, regardless of manufacturer: qualify the registers, measure and set the outter register cap-to-web gap, align bore, align hone, etc. My only recommendation specific to machining the CAT caps is to take slow, light cuts when align boring; don't just plow through with big rough cuts to get to the final cut/hone (be sure to express this to the shop that does the align bore and align hone).
They come with new outer bolts (you are expected to re-used the OEM main bolts) and even a pilot for drilling the outer bolts (the pilot may not last for all 6 outer bolts, so think about getting extras from an engine tooling supply house). I see no reason why you couldn't drill the caps to accommodate the OEM block's dowel pins. If you want to replace the offshore bolts with ARP or something like that, that's up to you.
I understand your weariness about CAT products and won't dispute your general concern. Currently, my opinion on CAT is to watch out for those components that are made up of moving parts (rocker arms, waterpumps, harmonic balancers, etc), but not necessarily a single hunk of steel such as a main cap. Remember that there once was also a time when most everyone bashed new-comers Eagle and SCAT because their parts were failing, but today they have their act together. I think that CAT is slowly working their way up the ladder, but personally I will use only their solid parts such as connecting rods and main caps and I will make sure they get a thorough dimensional inspection...but shouldn't all parts get such an inspection in a high hp build? By the way, this is what I was originally alluding to when I said, "they are a single piece of billet steel which you will fully machine for the application anyway." Just be sure to check everything out.
Right now on Ebay, when I type "460 main caps" into the search engine, I find 4-bolt main cap conversions by Programm (<---U.S. made of 1045 steel), CAT, and ProComp. I prefer the CAT caps over the ProComp caps (the ProComp caps don't include the outer bolts nor do they include a drill pilot....and frankly I just don't care for ProComp parts....). Of the three brands noted above, the Programms are U.S. made, are made of the best material, and are the strongest parts.....but the CAT's are easily the strongest part of the cast iron block once they are installed (ie something else about the block will fail from execessive power before the steel main caps will).
Here is a link to the cat caps, which actually do come with hardware for the outer bolts.
As has been discussed here before, the factory main bolts are widely accepted as being very high quality. Mr Kane has himself suggested many times that he believes the factory bolts to be superior aftermarket stud kits. There would be no need to spend money on additional hardware.
Again, I'll repeat this for you.
$400 for a good Dove-A block
$55(59) For the caps WITH bolts
$450 for the machine work.
There again, a grand total of around $900, which is much less than half the price of an a460 block. Obviously the a460 is a stronger piece, but it also costs much more. Check your math. A factory two bolt block has been deemed sufficient for 750 or so horsepower, the converted Dove-A setup covers the gap from there to well over a thousand horsepower. Unless you NEED the bigger bore capability, the Dove setup is very appealing in my opinion.