Unless you need the long action to make up a super duper magnum of some sort you would be better off to start with a sporting action. The conversion costs on old military actions are very high if you want to have it done properly.
Even getting a sporting action set up with a new barrel and stock is not a cheap proposition--I just had a 35 Whelen done on a Win M-70 action and when the dust settled the cost is over $1,000 including the donor action, stock, barrel-chambering, fitting and blueing.
FWIW, 44Bore