With these vertically split crankcases it is always necessary to heaten them up in order to install the bearings. When the bearings are too loose because of wear, you can use Loctite 603. After inserting the bearings you can push the oilseals in with your thumbs (use a little LM grease).

Replace, if possible, all bearings and oilseals. It can take a while to find them all, but that is nothing compared to the missery when you later-on find out that just that one bearing that you did not renew was bad after all.

Fitting the 2 crankcase halves together I always do with socketbolts. It is easier to torque them (11-12 Nm) and you do not see them anyway. For the crankcasecovers you can use the nice original PH3 screws. I always use Loctite 574 for this operation, it is perfect and also removes easily. I use it also very thin on the sidecover gaskets as they are normally also quite worn on these old bikes.