Re: Barrel blocks
I don't believe you'd have a problem with a block in the A-Series stocks, but you would need to consider the stock width first, then how much you'd need to leave on each side to maintain stock rigidity. Next, the side thickness you need to retain rigidity on the sides of the block would be different with steel verses aluminum. This will tell you what the maximum diameter of the barrel could then be.
The maximum length of the barrel would also hinge upon the taper of the barrel to a point. I found 30" 1.25" - 1.35" dia barrels without blocks are used, but most are on larger diameter and sometimes longer barrel tennons, but some are not. Bedding surface and bedding life was the main thing in question. The barrel block removes all stress from the action (if freefloated) and also provides maximum bedding surface, also being a zero flex recoil lug ta boot.
For the Rem 700 in 30/338 Lapua Imp that I had done, it will use a barrel block with the 1.35" dia tube, but it works fine without one presesntly.
My brothers Rem 700 in 338/378 WBY has a 32" bbl tapered to 900" at the muzzle, and a Holland brake in addition to that. It's in a Choate Sniper stock with no barrel block and works fine.