Okay, I've had this newly (older now) machined 350 shortblock in one of those nasa bags for about 4 years now. Still looks like day one. Eastwood and others have these. Anyways, it has flat top pistons 60 over and the cam is unknown. I'll probably change it if I can't find what it is.
What I am looking for for a winter tinkering project is a set of heads for this. I have no idea with the flat tops on the small block Olds what compression ratio I would be running with the different heads. 5-6-7? Just looking for a solid street engine. I also have a set of G 71 big block heads but I think the change over would not work. What I am looking for is around 9.5 - 10.0 compression.
Anyone have a set of heads laying around that will work with this? I just need a starting point. Thanks for any advice.

 

#8 heads from a later smog motor should get you about 9.4:1 compression with a 0.040 head gasket and flat top pistons. You be just under 9.6:1 if you milled a little off the heads or used a thinner gasket. #8 heads get a bad rap because of the large (79-80cc) combustion chambers, but they really flow pretty well, from what I've been told.

 

yeah I've read the #8 heads have a chamber the same size as the 4a 403 heads. A little work on them and they run just as good as the 5-6-7's. 5's are touted to be the best for the 350.. and will probably give you the biggest compression boost. Just be careful if you take too much off the heads you will also have to mill the intake so it will sit lower and match the ports. Kind of a PITA.

You CAN use the 455 heads on that motor, however you will NEED to use a Performer RPM intake because the ports are larger and there won't be a mismatch. You can also use a cast 403 intake as those ports are larger as well. Just take a little time and a bit of gasket matching. Not really recommended unless you are going full on racing. (I know of a 403 with E heads running 11 second runs...) Just not really worth the trouble either IMHO.

John