Help needed to identify early VW bearings.

[johnbrad]

I would be grateful for any help in identifying replacement bearings I need for an engine rebuild. I am trying to rebuild a Stamo aircraft engine
which I believe is a conversion from a 1950's VW engine with mag-alloy crankcases. The engine size is 1488cc with a bore of 80mm and stroke of 74mm. Nominal crank sizes are 50mm and 40mm (front) main bearing journals and 53mm big-end journals. Which model/type of VW engine should I be looking at with a view to getting some new main bearings and big-end shells?
The existing crank has had a 0.5 regrind and looks to be serviceable. The only clues I have are Nos. 1787 and 71-1971 on the big-end shells but nothing marked on the mains. Any help at all would be greatly appreciated.