Colin,
Don't put too much faith in this but I have a drawing I made many years ago when I had a (3-brg) case plugged and re-drilled, I placed the locating bolt hole 1.875" back from the front cover joint face. That engine is still running! If this for an engine with 1.5" big ends I'd worry more about cam clearance than perfect alignment of the gears..
I recently bought SAE660 bronze for a gearbox bush, worth a look at "Metals4U", priced reasonably and they will supply small pieces as required. Also in 'tubular' form for bushings.
Don't put too much faith in this but I have a drawing I made many years ago when I had a (3-brg) case plugged and re-drilled, I placed the locating bolt hole 1.875" back from the front cover joint face. That engine is still running! If this for an engine with 1.5" big ends I'd worry more about cam clearance than perfect alignment of the gears..
I recently bought SAE660 bronze for a gearbox bush, worth a look at "Metals4U", priced reasonably and they will supply small pieces as required. Also in 'tubular' form for bushings.