I am rebuilding my 454 and will have to change pistons as the past owner had flat top pistons in it with the 291 heads it does not work too good!!
I can get a pair of 781 heads from a wrecking yard. ARE THESE AS GOOD AS THE 049 CASTINGS? I can also get these, but at a much higher price. What neeeds to be done to the 781s to make them work.. Also what pistons are needed to run on 91 octane gas here in HOT Arizona? I am NOT looking for the fastest car around...... The Chevelle has P/S P/B and factory AIR I only take it out to car shows Any Cam recomendations? I now have an ISKY 264 hydrolic flat tappet cam . Thanks for any help . Gene

781's and 049's are identical pretty much...
I'd use pistons with at least a .133 dome to get some decent compression with open chamber heads (about 9.5 to 1 or so depending on head gasket thickness,piston to deck height,etc)

And AT 9.5:1 , I suggest you take a look at Chris's cam.

The general routine for building up a set of 049s, or 781s, is to reseat them with larger seats and swap in big valves. This operation, if done correctly, will really wake up the heads, combined with a bowl blend, you can make the kind of hp/c.i., that pushes heavy cars into the 11's and lower.

I'd say go with the least expensive of the two, but check the heads for cracks, etc. Also, ensure your machine shop has a Serdi, or similar guide/seat machine, and knows how to use it. They'll open up the area behind the exhaust valve some. Be best if they had experience in this operation.

It'l idle nice and have penty of snot!