Can I make this work on pump gas?

IMO, I think you would be better off lowering the static compression ratio. Maybe even another cam, too. Usually putting 360 heads on a 318 is a bad thing, but it might be the thing to do in your case if you could find some that spec out around 75cc or more. IMO you should lower the SCR about 1 full point if this is a street car. JMO, I am sure others will argue.