CP,

For tooling (reamers), check out:
www.travers.com
www.use-enco.com
www.mscdirect.com
www.mcmaster-carr.com

They have decimal and metric hand reamers which should get you very close to your target. The above links will have some materials in stock, but there are many other small-quantity metal suppliers on the net. edit: I just checked McMaster - they have 3/8" diameter 544 bronze for about $12 a foot...

Yes, there is a magic number for "crush" or interference fits for bushings, but it escapes me at the moment. Maybe vicman or toad will catch this thread and chime in - lord knows they'll be much more knowledgeable than an amateur hack like me!

I highly recommend sitting down and reading Ron Chernich's Model Engineering and IC Engine Projects web site - especially his engine construction articles! You can find it here: www.modelenginenews.org

Anyhow, this should get ya started while others chime in...