At Higher altitudes one can also advance the ignition timing, however, in your case since you are starting near sea level in San Jose, it would be a little awkward to keep fooling with it every time. I used to live in Mammoth in the early '60's, advanced my 134" Jeep engine that way.

You could also remove the head, do a valve job, mill the head .062" for slightly increased compression(new head gaskets are available) but then is that more than you want to do?

Ed

Last edited by EdPruss; 10/12/2018 2:54 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.