Max cut off head while still keeping correct rocker geometry

Hey so long story short I have a head with quite a bit of porting done to it. The fire ring groves in it are not correct and roughly .035-.040" would need to be cut off to have a fresh surface again. How far can these go? How much can the valve tips be trimmed? What are my options? I know I can get shorter pushrods to correct that side of things.

Also on the same not because I searched with no great answeres, how does everyone feel about exhaust to injector hole cracks that pressure test okay and are not visible in the seat.

If everyone says no throw it out too big a cut or why play with cracks, thoughts on aftermarket head quality? No good answeres on that either

Thanks!

I have had good luck with promax aftermarket castings , seen few flaws with head hardware none with casting ..

Subd. Got a hear that would need .030 off it to take rings again.

If it pressure test. Run it.

Short story long this machine shop originally cut head for o-rings. They somehow cut them in an oval, after it failed and we found the ovals we decided to try and recut fire rings over the o ring grove. It ALMOST got rid of old grove but after running it and failing yet again it's time to go back to a blank slate and do this right. As much as I want to run from this shop they keep footing the bill. So last week they bought me a new aftermarket head cut it flat did a valve job and cut it for fire rings. Well the idiots cut the groove too wide of an OD, so now that head is junk to me and I'm lost on what to ask them yo screw up next

what a joke of a shop were u located ?

Upsate ny
Carl mcquillen racing engines is the shop

Holy crap that's nuts. Amateurs. Might I suggest Castner's Performance in Penn Yan. They may be too backed up for you right now since its the beginning of pulling season but who knows.

Also I am sure you can deck the head down enough to make it flat again as long as the valve depth is reset. I'd give it a shot, might as well, not like the head's any good anyways otherwise.

The main thing to worry about is valve to piston clearance correct? I was considering taking a decent amount off my head for the purpose of unshrouding the valve, and then just running the thicker head gasket to bring the valves back up away from the pistons.