Good news, at least from the Dillon front...
They sell a 450/550 shellplate for the .25, .30, and .32 Remington family of cartridges, as well as the powder funnel bushings. I use them on my 550 press.
Minute-of-Deer equates to about 1.5 - 2.0 MOA out of the above pictured gun, using the Lyman tang rear sight and my 170gr handloads. I tell myself it'll go into the Wisconsin woods for whitetail one of these years. Then I remember that I'd spend entirely too much time trying to retrieve the brass after I took a shot out in the field, etc. Lord forbid I shoot all 5 rounds and go chasing their brass!
Problems: The recoil to your shoulder isn't as subdued as you'd think a long-recoil design would be. Maybe it's the double impulse of both the cartridge, then the barrel and bolt hitting their rearward travel stop.
Also, and this can be a serious one, the earlier Model 8 Remingtons DO NOT have a firing pin rebound spring. This means that ammo should be fed into the chamber from the magazine, allowing the bolt to pick up and chamber each round. Under no circumstances should you simply chamber a round and let the open bolt fly home into battery. You'll get a slamfire, just like the one I got in my garage several years ago with the above pictured Model 8. I ended up disposing of my trousers when it happened to me.
Save yourself the trouble. The drag or friction of stripping a round out of the box magazine slows the velocity of the bolt enough to prevent slamfires. You might get a light dimple on the cartridge primer this way, much like a M1 Garand, M14, or AR-15/M16. That's also the reason you see the SLED clips used for single-round firing of M1 Garands.
The later Remington Model 81's incorporated a firing pin rebound spring to prevent this little "surprise".
Floating around out there are Model 81's that were originally chambered in .300 Savage. That's a pretty powerful cartridge for the old recoil-operated autoloader. But some folks couldn't leave well enough alone, and a .308 Winchester chambering reamer found it's way into those .300 Savage guns, creating a Model 81 chambered for the more powerful, and higher pressure, .308 Winchester. Steer clear of those guns, you're just asking for trouble.
Hope this helps!