I'd say your thoughts are pretty well on the money. The 7x65R is a fine calibre for those animals and will do very well on your local game as well.

As for SxS or O/U, its really your preference. A chapuis in either is a thing to behold.

You've got a 450/400 for the heavier end of things, with those two rifles, particularly given your special, er, biometric gifts, custom is doable.

If you've got the $ and are thinking of something really special, Giles Whittome in the UK does some nice stuff, he's also about your height.

Good luck!