I built a sacrificial lamb for testing of the roots engine for my 70 Challenger.
Built it out of what I had laying around out of old 318.
Dipped the block, new cam bearings / soft plugs.
Had the crank turned, honed the cylinders.
New rings, opened up the ring gap.
Grabbed a set of 2.02 J heads off my shelf, sent them to the machine shop, new valve job, slight surface cut for flatness.
Put it together with new bearings, oil pump, cam, timing chain, studded the heads, and added a windage tray.
It ended up with 7.5 measured compression.
I have less than $1000 in the whole engine, not including the supercharger.
I will play with pulleys for different boost levels, I am going to start out with 10% under-driven 6-71 set up, and sneak up on the boost level.
I know my limiting factor will be the stock cast pistons.