150 PSI (technically it's 148 or 151 I think) is 10:1 compression ratio
220 PSI is running a 14.6:1 compression ratio.
I've never really measured compression, Angel just kinda showed me how to guesstimate compression one time for the low side so I just use that to eliminate compression when diagnosing a no-start situation
I haven't ever modified a head except for a Batavus Bronco I got from a dump and would sand a puch head down on a cinder block the Scuba Steve way to regain compression when the blown out rings inevitably lost more slowly.
I'd say a Gila on a V1 is generally like 185/190? I think that's a good some but you do need to manage heat in high load situations. Gila does good at surviving heat tho. They do blow head gaskets so there's that