Original 50 info

[trajectory]

Hopefully you can identify it from pictures of other model 50 varriants. The crack may repair well but it depends on a few factors lilke where it went, why it went & if it closes up well plus a few other things too. I am sure you can get plenty of advice from others on here. Stocks for the 50b types seem to come up for sale infrequently so repairing this one & getting it done right may well be pretty important. Not common for other model 50 types either.
If its a model b there should be a large metal rear sight that can be moved from the tap area to the rear of the cylinder & it should have a detatchable eyepiece with eye cup. If you are really lucky you might even have the adjusting tool too. If not making one out of a bit of brass & 10 min with a small file might be the way to go. To adjust the sight for windage a spring clip needs depressing as the adjuster is turned, so a propper adjuster is helpfull. Lots get mangled with pliers & they deserve better than that.