Rear main leaks always make me nervous, they can go from small to all the oil comes out really fast. Yours should be a 2 piece rear main so if you can get the oil pan off without pulling the engine you can change it in place.
if it is a really good restoration one like it sold at mecum auction last year for $200k. they won't get that on KSL but it could possibly be worth that much
Last weekend my wife and I were looking for something to watch and Predator happened to catch my eye, she had never seen it so we watched it. Now she is enjoying all the cheese filled 80's action films. We watched both predators last weekend, Rambo First Blood on Monday, Commando Wednesday...
For that distance I would say a 7mm rem mag or 300 win mag, if you want to get fancy 300 PRC is a great round but is a little on the spendy side. As for rifle I have never had an issue with any Savage arms I have owned or used. For a scope maybe look at a 4-16. I don't know what the weight...
You'll want to upgrade your transmission if you are thinking of hitting those kinds of power numbers. I assume it's an automatic, the 5r110 doesn't like the kind of power it takes to push 400 to the wheels, inside might become outside pretty fast. They are rated for 1100lbft input post torque...