302 are 64 cc chamber while the 920 is bigger I believe, like 66 or 67 cc.
302 are induction hardened exh seat but that's not reliable after they cut through the hard surface during the valve job.
I have heads if you head some and can provide them in a few forms, cores, ready to run, and or ported ready to run.
They flow around 175cfm by .500 'stock'
After porting they flow 200cfm by .500 lift. Stock valves still.
I updated the chart on page #202 with information from Galen's parts interchange book and Larry Shepards "How to Hot Rod Small Block Mopar Engines" book. The 302's are listed as 56-65cc and the 920's are at 57-64.5cc.