915 rebuild, what to replace ?

[projekti]

First of all, thanks for all the good threads here on 915 rebuilds, without them I would not have even dared to start to take my tranny apart.
The tranny i´m rebuilding will stay in the car ( 1973 T ) only for 2 summers to come so I will only replace what i must. I put it in last summer to find out that it grinds badly when shifting into second and third, the rest work just fine.

The dog teeth on second have this half moon shape so I suppose i must change it is this right ?



The syncro on second has this wear on the back side so I´ll change it also. What do you think caused this ?








I believe that the third dog teeth are ok, yes ?


But the syncro must be changed


And at last one more question for the real pros,
The cylindrical roller bearings are of course of very old design, riveted brass cage and small rollers with big space in between as you can see here below



Can these be replaced with new modern once ( same ID, OD and width) but with either pressed steel cage or polyamid cage, or do they have to be these old once ?

Thanks