Hi Kevin,
You're asking the wrong person

! If I were building a customized rifle on an Enfield Action.....it would undoubtedly be either the .338/06 or one variation or another of one of the Whelens.
Why? You already have lighter calibers. A big bore cartridge....built on a reasonable case, (like the 06 case), can be loaded to do many things. For example....in .35 Whelen or an Improved Version you can load .357 caliber pistol bullets to slow/moderate velocities and have a nice plinking, small game rifle. You can load either 180 or 200 grain jacketed bullets to intermediate velocities.....ala. .35 Remington....and have a low recoiling medium range "deer rifle". Or you can put a good 225 grain Ballistic Tip at maximum standard pressure and reach out a "long way" to touch something. Or you can take a super premium 250 or 275 grain bullet and have a "medium bore" stopper for thin skinned dangerous game. And that's just one caliber!
Now think of all the similar possibilities with the larger bores. And the larger the bore.....the easier to obtain "hard cast lead bullets with gas checks" for lower velocity plinking, hunting, etc. You can even work up greatly reduced loads with the big bores using lead round balls and turn them into a lightly recoiling "squirrel rifle"......if you like. They are just plain fun. Not to mention extremely lethal on big, tough, game with their "serious loads". They are the kinds of calibers....and velocities...that all the game of Africa was taken with.....and that continent was settled with! (The 9X's, the 9.3X's, the .350's, the .375's, and the .40's.......all at moderate to reasonable velocities.) Get the book!

Really, you owe it to yourself!
Dave
P.S. Sorry about the money for the house......but I can't help myself!