I've read about those in the ancient history books many times. I've always wanted to build one and put it in a early deuce or something. Most guys now say it's just a waste of time and if it's not at least a 383 why bother... I say because that's what they did in the olden days back when mouse was inventing the wheel.
If you build on e of those mouse motors they will hold their own. 64 CC chambered double humps with 2.02's and good exhaust valves and a set of flat tops puts you near needing race gas.
I turned mine 6500 on a regular basis and it saw 6800 still pulling.