James, to the issue of strongest action.....I'd guess a tie between Remington 700 and the Savage bolt action. However the Winchester M-70 push feed, Sako, A-Bolt, and Howa are also very strong.....

Actions with claw extractors are also strong until we rupture a case. The claw extractor is not a positive feature at that time!!!!

The Remington 700 (and others that fully enclose the case head) will tolerate many reloading mistakes and will hold enounormous pressures and not let gas into your face!!!

The mauser 98 is a fine action and has been used forever as a basis for sporters. However in the end you still have a '98 Mauser and resale goes to pot unless an extremely beautiful job is done. Many people want their dangerous game rifles on the mauser.

I've built several customs on Mausers and won't ever again....it's actually less costly to start with a M-700, or a M-70 or even a commercial mauser and in the end a good resale is possible.

Either of the .338 or .338-06 are superb choices and it depends on the action you find as a donor.

Best of luck.....have a ball.