516 head rebuild

Judge'n from your guide picture those guides look almost new. I would guess your grandfathers seat grinder is a Sioux? If it
is it will have guide pilots for the stone holder, sized .000 +.001 +.002 +.003. They can be used as a go-no go gauge for guide
size, no need for a $2000 dedicated guide mike. If desired a standard machinist pin gauge set will do also. Under $100 from
a machine shop supply. If a machine shop tells you it is extra $ for a 3-angle valve job go somewhere else, that is a CORRECT-
STOCK valve seat regrind. Look in any factory, motor, Chilton .ect manual that covers it. You need the 30deg and 60deg cut
to set seat with and locate it correctly on the valve. No matter what your combination is, the quality of your valve seal is THE
most important factor in power potential or just plain run. Take a Formula 1 head and screw up the valve job with the best of
all parts and the worst flowing brand X head with a "correct high quality" valve job, brand X will out run it. Let alone run.

What these great guy,s-gal's are telling you is if your valve/seat grind is junk, you won't get out of the driveway let alone run.
What head, does not dictate how it will run, the quality of the valve job does period. From formula-1 to a Chinese go-cart
engine, if your valves don't seal, what do you have.

edit: your seat grind/runout is all based off the guides.
Rick