you have a few options... get a blank tube with the appropriate size hole and rifling twist and have a gunsmith thread, crown, chamber and setback the barrel and install on your action... or you can go with one of the pre-threaded, chambered and crowned barrels available and then the gunsmith has to bump the shoulder back until proper headspace is achieved... if the gun is blued the barrelled action will need to be refinished...

once had a 700 rebarreled and it cost me just about as much as the rifle did... in the neighborhood of 500 bucks.. with a shilen tube

the latest rifle (700 rem) i built i did entirely myself (and i'll do all of them myself from now on - but as an advisory i am a mechanical engineer with a good number of years of machining experience)... bought a Douglas XX PTC tube and bumped the shoulder in the lathe and put her together... (not QUITE that simple, there is a fair amount of setup, disassembly and reassembly)... still had to have it blued since i don't have my bluing setup finished yet.. altogether i have about 350 bucks into this method... i resold the headspace gauges after the gun was finished and i was satisfied... the barrel was about 218 bucks in 4140 in the white... bluing was another 125 in a matte finish... so if you have it done by a gunsmith it's gonna cost about the same as method #1 by the time you pay labor...