Bob,

The Steyr M95 straight pull (military version) is pretty common and inexpensive. A lot have hit the surplus market lately. Cannot comment on how available sporters are. The Steyr straight pull action is really nice and smooth. A great platform to make a custom rifle. Can you post photos of the rear and front sights? I see yours had double set triggers. Nice.

IMR 7828 will be way too slow for the 8x50. You might want to stick with IMR 4350 or something a bit tad quicker. for this case size. 4831 will also be on the slow side for top velocity.

Keep us posted how it shoots.

Corbin