Welcome Nick! Sounds like an awesome project. For your rings, you just go buy a nice cc set of rings you can get away with, and find locally, eh? And build to those specs and clearances.
We have a local Guru that likes to smelt down aluminum and build(mill/lathe) things out of what he smelted. http://motorbicycling.com/showthread...=16550&page=15
What is your cc limit over there? <-curious