Don't automatically reject the heads with larger combustion chambers. The 1954/55 "low compression" head can be made to equal the compression ratio of the 848 by milling .090" off the head gasket surface, and recessing the intake valves back into the head the same amount to protect the edge of the valve from the flame front as it travels across the face of the head. That modification was pretty common with hotrodders in the late 1950s after the 848 head was produced. BTW- - - -stainless steel exhaust valves for a Chevy small block V8 are a drop-in fit on all the stovebolt cylinder heads. There's no need to drop a truckload of dollars installing hardened valve seats!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!