I don't know when Craig will see this,,,,so Craig if I may, I'll answer the question. The Thor heads, and the ProFiler heads, and the C-460 heads all use the same exhaust bolt pattern. The pattern is called the Pro Stock bolt pattern and quite a bit different from a BB Chevy bolt pattern.
Furthermore, within or relative to that Pro Stock pattern, all 3 of those heads mentioned above, have a different exhaust port exit position.
I don't know how to post a pic on here if you send me an email I can shoot some pics.
These are FabShop headers w/ merge collectors. 1 set is 2 1/4- 2 3/8, 2 1/2 all downs. Both sets will accomidate Profiler, C-Head or, Thor head port design. $800 a pair I also have a set of Hooker upswept for a 429 CJ head. $ 425.00
The Fab Shop laser cuts gaskets for any header design.
We also ship world wide...