What I was thinking of doing:
1...OEM unshaved head for "jig" oh wait you can't SAY that,
2...Make the blank plate and index to head surface
3...Make at least 2 studs in lathe, grind to points for centers
4...Install studs in heads, install plate and tap to obtain bolt centers
5...Drill small pilot on these centers
6....Install in drill/ mill ream to clear bolts
7....Install plate on head using these holes with bolts and obtain centers for remaining bolt holes, drill small pilots
8....Ream all holes to clear intake bolts
9....Install plate and pilot tubes on head with long bolts to clamp and weld pilot tubes.
So the flaw I see? is that the tubes will now be large enough to clear the intake bolts, rather than the drill size for the tap. This can allow some slop, BUT you can buy thin wall tubing (brass?) which might be a work-around, inexpensive, and easily replaced when worn.
Maybe I could ream and install helicoils in the head to accept 5/16 bolts and that would then allow me to use 5/16 bolts to "jig" the thing together
