Forget the turbo......you don't need it. Having years of experience around 18 wheelers, and having owned and fixed up a classic International 9670, I can tell you that the venerable Detroit 6v and 8v series two stroke diesels were pressurized by a gear driven roots style blower. Later on the silver series models, a turbo was added, though it only added to the pressurization. It wasn't really necessary to make those engines work well. By that time, an 8V-92 Detroit diesel at 736 cubic inches would make from 435-600++ HP at 2100 RPM. It was a giant V-8 at 92 cubes per cylinder. Just some interesting stuff......

Basically, what you can use is a roots style mini compressor/blower for a motorcycle engine. I think they exist if I'm not mistaken. That will give compression in the crank case without valves and is immediate and mechanically direct.