You could convert it to 300 Win Mag with minimal effort, just run a reamer into it. You may need to do some magazine work, check that first. Or you could rebarrel to one of the 2.5" magnums: 264 Win Mag, 7mm Rem Mag, 270 Weatherby, 7mm Weatherby, etc.
Interesting bit o' history: in 1964 Winchester started introducing the 2.5" magnums, designed to fit in a "standard" length action because it was the most common length for both milsurp and commercial actions. Winchester was releasing cartridges one at a time, to make the most of the exposure and hype. The 264 and 458 had been introduced a year earlier, causing a huge media event and much hoopla, and the brass was available. Norma, seeing where this was going pretty quickly, introduced the 308 Norma Magnum, a 30-caliber magnum based on the 2.5" case, and got a lot of press for doing so (Remington did the same for the 7mm cartridge). This kind of torqued the folks at Winchester, who could not just introduce a similar cartridge with their own name. So they decided to outdo themselves, and redesigned the cartridge they already had ready for release so it would beat the 308 Norma Mag by 10%. They lengthened the cartridge, gave it a distinctly more blown out case with a sharper shoulder, and managed to gain about 150 fps over the 308 Norma Mag. They released the cartridge with much fanfare, and since the gun rag writers were always cheering anything that went faster, they jumped right up and cheered for the big boys at Winchester. For several years, the 300 Win Mag and 308 Norma Mag were all the rage, then the Winchester started to gain traction because no one chambered factory rifles for the 308 Norma Mag except Schultz & Larson (a Danish firm) So long story short, Winchester's media plan to trickle their new developments out one at a time kind of bit them in the butt, but it all worked out in the end. The 300 Win Mag was followed by the 338 Win Mag, which was later wildcatted to 30-338, an almost exact copy of the 308 Norma Mag. History repeats itself.