How hard is it to rebarrel/chamber a Win Model 70 Classic, Sporter LT (Left Hand), in 30-06 to another caliber. Say .280Rem, or 25-06?? Is it just a matter of having a smith change the barrels, or will there be feeding problems, etc, to work out??

Because the round you suggest are basically .30-06 necked down, a simple barrel change should do the job.

I see no reason why a simple barrel chage to those calibers would not be all that's necessary. Just get a couple of rounds of .280, .25/'06, etc., take the striker mechanism out of the bolt, put 'em in the magazine, and SEE how they feed. They should feed just like .30/'06 cartridges!

Bear in mind if you wish to change to a smaller diameter bullet, you'll need a new barrel. If you go UP, like to a .338/'06 or .35 Whelen, you COULD have the current barrel renbored/rerifled, then chambered for the bigger neck diameter.