gssixgun,
1) I agree with the others - it sounds like you just want a 35 Whelen (because based on your battery you certainly don't need one.) And that is 100% fine. A 35 Whelen AI was the second custom rifle I ever built and I have had mine for 30 years and love it.
2) I have two JES rebores, both 1903 Springfields. One is a 338-06 and the other a 9.3x62. The 9.3 drives nails - the 338-06 has been problematic. I'm interested in why you are choosing the rebore as your primary option instead of looking for a rifle that is already a 35 Whelen. If it were me and I wanted a 35 Whelen, I would begin by looking for a good 35 Whelen.
3) Brakes - I've never owned one but I don't care one way or the other. If you like them, get one, as the loads I mention below will flat get your attention if you have an un-braked 7.5 pound rifle...like mine.
4) The 225 TSX at 2600 FPS - you are selling the Whelen WAY short. The 250 Nosler Partition will easily do 2650 to 2700 with PP 2000-MR or CFE-223. The 225 TSX will easily do 2800FPS with 2000-MR. The 200 TTSX will approach 3000 FPS at about max pressure with PP Varmint. I killed a nice bull in 2019 with the 225 TSX and recovered it under the off-side skin (my only ever recovered X bullet) after it broke both shoulders and dropped the bull on the spot. It weighed exactly 225.0 grains - doesn't get much better than that.

Enjoy your search and your hunting!
Rex

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