Since I'm sitting here, recovering from a hip replacement, I'll give my .02.
I have owned all 3 calibers. I started in '95 with a Mod 700 Classic in 35 Whelen, had it rechambered to the 35 Whelan Ackley Improved. I fireformed my Ackley brass with a warm load in 35W new brass and the Speer 220fn jammed into the rifling. Made perfect brass. I loaded the 250X and went to South Africa. I was running it close to 2600fps ( 9.3x62 territory) and killed zebra, red hartebeest, kudu, gemsbuck and blue wildebeest with it. Perfection. I cam home, thinking I was going to go back for a cull cape buffalo hunt, so I had that rfile rebarreled/converted to 416 Taylor. Bad choice, rifle too light/brake too loud, off it went. I then had a Mod 70 FWT rebarreld to 9.3x62. Components were hard to find then ('97) but I played with the 286 Nosler. Gave the rifle to a young family man who killed elk with it. I went through a .375 H&H & 375W,340W, 300WM (South Africa/Namibia), then a 338WM, then another copy of my first Mod 700 Classic. I took it to South Africa in 2002 but with the 200X ( it was going 2970fps from the 35 Whelen Ackley Improved) I killed a Black wildebeest at 347yds and another zebra at 250yds, perfection. I played with a Mod 750 in standard 35 Whelen, an excellent shooter and 100% reliable. A like new Browning BLR 358W shot well with 200X, both too pretty to hunt with and the 35 WAI Mod 700 was too jealous to stay at home on hunts. Off they went. I bought my SIL a CZ 550 FS in 9.3x62 as a welcome home from Iraq present. its a good shooter. I tried a Mod 77 African 9.3x62, but it had headspace issues and I was pressed for time/money, so sold it. Took the 35WAI that Fall too. I tried a Mod 700 Classic in 350RM. To "me" it was just a 35 Whelen that kicked hard, about as much as the 35 WAI. I was also limited to the short action. Off it went.
I then had that wonderful Model 700 classic rebarreled/converted to the 358 Norma Magnum. I would have loved using that rifle, but Obammacare taxed Ministers on their benefits and by the time that all got sorted out, with penalities, etc, I had to sell off everything, everything, to pay my ransom!
So...while I have gained a few rifle back, none are in 35 nor 9.3 caliber. My hunts are fewer apart and no more Africa for me.
I would suggest two options (neither include the 350RM) (a) The Nostalgic Route = A 9.3x62 in a CZ 550 FS, or a Mod 77 African. More American fix up an old 1903A3 in a standard 35 Whelen. Go with a 14 inch twist. 1x5 scope (Option 2) Set up a good action of your choice ina synthetic stock with a stainless ( maybe add cerakoting) 24 inch in 35 Whelen standard ( with the newer powders we have no need for the Ackley version) or 9.3x62. Put no more than a 2.5x8 or 3x9. With a 200 TTSX in the Whelen you cover the same ground as a 300WM and with a 250 in either 35W or 9.3 you cover the 338WM and the 375. Your choice. figure out how you want to hunt, and where and match the rifle/bullet to that. Excellent rounds, no matter what you choose. (psst, I would still do a 35 Ackley just to be different! ha) Have a ball pard.
