It's impossible to build high output engines without modern cnc grinding and carbide cutters.
That's how we won WWII! How else do you think the USA built all those massive radial and v12 engines for our Army air Corp? With incredible alien cnc technology of course. Can't do anything of note without carbide and computers, of course.
Neway cutters seem to come up a lot with the diy crowd. Also plenty of grinding kits. Grinding is an acquired skill that takes practice and an knack, but can be learned. Cutters can chatter, but same deal - they finesse and technique can go a long way.
If you've ever run a lathe or have machine experience I'm betting the learning curve isn't too steep. If not.. Well there's nothing can't be learned by doing.