Re: Re-barrel to any Ackley Improved. The standard cartridges are fine in the 740/760 series actions, but you want to stay away from the Ackleys in them. The issue is not pressure, safety or any of the normally considered problems, but is function/feeding. This is a good way to make one of these guns into a single shot.
I have an acquaintance who has a 760 which was originally a .35 Rem. This man is no slouch as a gun repair/gunsmith himself, so experience wasn't the problem. Probably about thirty years ago he asked Pappa Oscar to re-chamber it to .35 Whelen. Ackley, probably thinking he was doing the man a favor chambered it to the AI version instead of the standard cartridge which was desired. To make a long story short, he is, last I knew, still looking for a .35 Rem. barrel (factory) to replace the one in the AI which he has never been able to get to feed properly!
Even P.O. could make mistakes!