I agree on the clearances in relation to non pressurised lubrication systems, if I end up making a new shaft and bush then I'll try the EN36, it's the same solution employed in traction engine valve gear and is subject to very poor lubrication but lasts well.
I'm new to this forum so here comes the dull question, wall of knowledge? Don't ungerstand the offset but either so would love to see the post.
Cheers
Steve