setting up quench dome pistons for open chamber heads doesn't "require" machine shop work. i've done this many times. there is some measuring required and any chamber work can easily be done by hand.

setting up flat top pistons with closed chamber heads will still require measuring. before i blew a bunch of money on 915 heads i'd take a look at the sidewinder heads. the sidewinder heads with a light weight flat top piston and rod is where i'd be looking.