Most PRS rifles are short actions. However, don't let that stop you. The answer you seek is either the 6.5-06, 6.5x57 or 6.5x55. 6.5x55 factory ammo is available, however, it is loaded at extremely low pressures with safety in mind for the old Krag-Jorgensen and model 96 mausers. It can be loaded quite a bit hotter, but, due to the taper, requires regular trimming. The easy button is the 6.5-06. Quality brass is plentiful, no need to hot rod it.
I’d sell it and run a short action. Something with a lot of chassis options and aftermarket support. There are many factory rifles that would meet your needs for less than you will have in your build. Spend your money on ammo and your time on practice.
If you just want to shoot long range and not necessarily compete a 284 Win is a good option with decent barrel life. I wouldn't use SAAMI 284 Win. Lapua brass with a .317" neck and about .188" freebore is a good set up for 170-180 grain variety of bullets.