An Old Timer once told me...

With a 'lil' porting they flow what/or close to what a stock 360 head flows

the heads open chamber heads are like 68cc's while the 360 heads are like 72cc's

4cc's could be about 10'ish psi increase in cylinder pressure.

the int port volume is 124cc for 318 heads and 155-160cc's for 360 heads depending on wether they're 2.02 or 1.88 int valves