I'll be beginning to overhaul my 250 soon and I understand that I have a couple of easy options to increase the compression ratio; use 307 pistons or use a 194 head. Which of these raises the comp ratio the most? If I do both, will it still run on regular gas okay? I plan to use a small 4 bbl carb on an offy intake and stock cam if that makes any difference. Any info or suggestions will be appreciated.

'64 swb stepside (gone)
'57 1 ton
'53 phone truck
'59 swb
'46 1 1/2 ton
'68 swb gmc