Thank you for your replies.
I had a 70 mercury convertable with a 429 that got a good 16 mpg, and this is why I asked the question. I could not believe the gas mileage was up to par. I think with the overdrive this truck should be capable of 12 mpg, but who knows. I knew that i had to do someothing about the heads. but not know which engine is actually is, uncertain as how to procede. I do have a set of C8VY heads as well as a set of C9Vy's as well. The C8's go with another engine I have, but the C9's have no valves etc, and I have not been to pick these up since vatted. (very rusty) I also have a set ove D3's in the vat as well also rusty, but complete. I would rather be able to just have what I need built and ready to go on, but uncertain which crank and what pistons I have at present. Makes it tricky on what chompression I build for. I want to run pump gas with no problems, and not have to run a premioum , as it is not that easy to find around here. Armpit of the world don't you know. Smalltown USA southern IL.. I most likely need to pull the engine to be sure I get it right rering rebore etc. if neccesary. Major PITA, as I did not want to get that far into this engine. I thought about just building heads and slapping on when ready, but If I want decent mileage, I need to aim for about 9.5 compression ratio to get the best I can out of the poor stuff behind sold to us at exhorbitant prices. With the overdrive, I would think 12 to 14 mpg should be attainable with judicious ddriving, ;and 12 without holding my foot back. With the question of whetther I will want to keep the truck once mileage is in, I'm tempted to just do a bore scope and see what pistons I have, and what heads would give me best compression. Of course, If I don't do a rebuild, then I will wonder if it isn't the rings that also need replacing. Again a vicious circle. Damned if you damned if you don't. Should I get the gas mileage above 13mpg, then I most likely would keep the truck, as it is a great driver. Original interior in good shape exterior is good but lots of door pops and will need a paint job in the next few years to keep it pristine. Unfortunately it has the Explorer package with stick on stripes, and I doubt if these are anywhere to be found. Only one rust spot coming thru on the left rear fender well. about 2 inches long. I might mention , that at present own about 15 pickups and a few one tons, plus 5 cars counting the wife's. I really don't need the truck and have plenty more waiting in the wings to be liscenced. This in itself is becoming a problem as Illinois has jumped liscence renewal another 20$ this year. I at present have 5 liscenced vehicles. More than enough for the twoof us.