Well, if you hand load, I think a .30-338 Win Mag or 308 Norma Mag would be fun. .358 Norma Mag, great all-around, big game cartridges. .264 Win Mag, 7x61mm Sharpe & Hart Mag yeah... something from the past. Cheers
I have an itch for a 7/300 win or equivalent. You could use 120 vmax for the red mist or actually hunt with it using game or target bullets. Around 8 twist would cover all but the heaviest .284 bullets. All your existing 300 brass would be useful and a bushing change in your current fl die would mostly cover your bases.
A fast 7 is effective in the wind and downrange, but without the recoil of over-200gr bullets.
If you want a cheap rebarrel, try to find a factory take off barrel. I have replaced M 700 barrels and every one head spaced correctly. The only thing was the stamping on the barrel was 180 degrees out.
If you are a reloaded and are set up for 300wm, I'd stick with it. It's just SO hard to beat. I reload but wanted to move from 7mag to 30cal so I went with 300prc because I was starting from scratch.
The single biggest benefit with the PRC is they are set up to shoot heavy for caliber bullets but you can have a Win Mag throated for that.
I also feel compelled to share that I'm shooting 220gr 300prc at 3k fps and with a simple muzzle brake, it is much more pleasant to shoot than my 7mag. With my Thunderbeast Dominus suppressor, it's a cream puff.
I've engaged in a few conversations of late with your same question. Almost all the folks are thinking 7 Rem Mag. Its a good option to drop some bullet weight and a bit of recoil.
Since you have one of those, and if you don't want another, say in a fast twist rate, maybe its time to check out the short mags.
