Pop up piston, machine head to fit
Im with Tx, Bore the head, if the head is un planed u shold hav about 0.250 from gasket face to v/v face. your .350 lift cam, 260* duration im guessing, probly has .100-.150 lift at, in and around, near overlap, (its a nail head desizn so valve relives dont come in to play so much anyway) you should be ok in that respect.
The OEM spark plug with its extended tip prbly will get hit, youll need a retractor tip and with high compression that's what you run any way.
The machineist will probly mount the head on a rotory table and mill, but the job could be done on a lathe with a face plate too, and he will need a center to work off of, if you tape a sharp nail to the center of your piston you can transfer a mark to the chamber center for him.
If you run a 0.040 head gasket and you machine down 0.050, that should leave you 0.030 piston to head clearance
Piston v/v clearance at overlap should be around 0.050-0.100......
Should work.