New to the game, 1972 malibu, not original 350 engine. Right cyl head casting id #3986338x. Hard time finding cc and valve size specs. Would it be worth keeping these heads for a rebuild, possible stroker? Any info would help.

3986339 1968-79 307 - 350 1.71 / 1.5
3986388 1968-79 350 1.71 / 1.5
3986339....71......307/350......74cc chamber
3986339X...71......307/350......74cc chamber
3986388....68-76...307/350
3986339, and X 74.5cc 1.72 1.50 1968-79 car, truck
398633x 76cc 1.94 1.50
3986388 cc 1.72 1.50 1968-79 truck 350

HERES INFO i FOUND