Pics would be good.... I've been thinking of a similar project myself. Criterion makes the barrels for CMP. It would be worthwhile to see if their A3 contour has the step machined in the middle of the barrel. The project action I bought has a Remington A3 barrel that I had to have that step removed on a lathe. I like the way it looks now & it does not have the spline cut for the 03 rear sight on the barrel shank.

As for changing the caliber if the original barrel is toast, I would consider a re-bore to 338-06 or 35 whelen. I haven't used them myself, but I have heard positive feedback: www.35caliber.com

That said, my project has languished as I came across two real NRA sporters. Both have been modified, but have Lyman 48's and excellent barrels. One was restocked and the other received a white line pad and grip cap treatment. I feel both of these are a better use of my funds and time. If you are dedicated, these can be found for a fair price.

-Tom