If anyone can point me in the right direction, looking for ap, api and the regular ball info..

Wideners (www.wideners.com) and
Big Sky Surplus (www.bigskysurplus.com) (for up to 16" shells BTW)

As you've already found, published data is not available for 50 military bullets and surplus powder. Starting charges from a magazine said that with IMR5010 or WC860:
bullet weights of 647-650 grain start at 210gr.
690-700gr bullet------------- start at 205gr.
750-------------------------- start at 200gr.
800--------------------------start at 195 grains
Here's a site on the net that has data from his tests. I've found that his data is very close to my results and his load data does not exceed maximum:
http://www.sandboxpx.com/BMGRELOAD2.htm
Surplus powders do vary in burn rate so start low and work up.