No, the 66 and later 273-318 heads have the same size valves in the same position as the early ones, just the later intake bolt size and angle... The combustion chamber size should be close if not the same as what you have now...
If you put 340-360 heads on there, they will have larger valves and larger combustion chambers that will lower the compression...
I would recommend using the 66-67 273 head, it has the closed chambers on them and the proper intake bolt pattern...
Here's a set of 67 920 heads that I had done up by my head guy. They are for my son's 318 in his Challenger and my head guy did them up with the 360 valves and ported them... They have the smaller closed chamber for higher compression... You can get away with larger valves on the 318 because of the larger bore, but not recommended for the 273...
But if you get a set of these, they will go on and you can use the Edelbrock LD4B intake with them... (You will have to re-mount the coil somewhere as the manifold does not have the bosses to put it in the stock position. One moderator here had a clever solution to use a 340 six pack coil mounting bracket and it worked very nicely... Thank you for all the info. I really appreciate it. If I am lucky enough to locate a set of heads that you recommended will I still need to clearance the cylinder (Intake valve) or will they be ok to run "as is" I'm assuming they will be OK? I've had several B/RB engine B body cars but this is my first A body small block. I think you have me going in the right direction. Thanks again! Litz
You would want to look for these casting numbers for those type of heads, they are for 66-67 273 and 67 318 heads:
2536178, 2658234, 2658920
Here's a link for the head casting number reference chart:
MyMopar - Mopar Forums & Information - Mopar Head Casting Numbers 1959-1978
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