Dino,
I'll have to do some checking with regards to case length difference. Not sure at this time. One thing for sure though, you should be able to load almost any load for the 454 into 460 brass and not have any problem. Don't go below a starting load with real fast powders though. It is a big bone of contention among handloaders whether or not there is a certain phenomenon that occurs when you do that. I'm having a blond moment right now or I would tell you what it is called! (Actually a gray moment!)
The reason for filling the case with Trail Boss was suggested is because it would take that much to get things to happen. It has a super low weight to volume ratio. 4grs will almost over flow a 38spl case where 3.5gr of Tite Group or Bullseye isn't hardly visible in it.
The reason for wanting more case fill is for position sensitive powders. Say you have your X frame pointed to the ground and the load in the case only fills about 40% or it's volume. Where is the powder going to end up when you tip it up to shoot it. It will have the angle of recline according to the fill. Your flash hole in the primer area may not be covered with powder. Again, to hear some tell it this is MORE dangerous than having too much powder in a load. I don't know. Not going to find out either as I run my loads towards the top of most data.

The 460 shooters aren't shooting much is the reason why they don't mind buying ammo. Either that or they are loading a bunch of 45 Colt and shooting them.

Personally for your "plinking" rounds, if there is such a thing when talking about the 460, would be fine with ANY 45ACP or 45Colt bullet. If it was me I would be shooting my own cast 250gr LSWC with my homemade lube on it. The bullet type I have will allow me to push them to the 1800fps range. I need more than that? I'll tell you what I really want though. I want a turn at that mold Paul5388 uses from time to time. It is a 270gr +/- Elmer Keith bullet that would be ideal for the 460 IMHO.
If you want to get into extreme hunting situations on extremely large animals you may need different bullets but for anything here in the good old US of A my suggestions will work fine. Does paper or tin cans or bowling pins or steel plates or ....... really care what type of bullet hits them. Are you going to kill your target any better with a JHP than an FMJ?

If you are going to load some rounds up get some cheap Ranier/Berry 230gr TMJ and go shoot about 100 rounds out of your gun and have some fun. Get them up there in the 1200fps range. It'll be cool!

Be safe, have fun.

In the meantime, Hornady makes both a 240 and a 300 grain bullet expressly for the 460. Lots of load data for these - as hot as you can stand down to quite mild loads.

I'll chime in w/ a combination I've had some success with:
H110 (max per Hodgdon website's data)
260gr Nosler Partition
Redding dies (profile crimp & as much as I can apply in my 550B)
CCI primer.

This has proven to be very effective on whitetail & feral hogs in my 8 3/8".

I reload both 454 and 460 for my 8 3/8 XVR. I use Hornady dies for the 454 and Lee for the 460. The Lees work OK - but they are not the same quality as the Hornadys. I am not sure if I recall correctly, but does Hornady make a carbide resizer for the 460?
I typically load close to max H110, Winchester Large Rifle Magnum primer under Hornady 240 & 300gr XTP-Mag bullets.
If I shoot 454s and then some 460 (with no chamber cleaning in between) - the 460 cases can be a bit hard to eject...
The 8 3/8XVR weighs close to 5lbs - it does a good job of absorbing a lot of the recoil. The most uncomfortable 45LC I have shot was from a Taurus Judge (very light) - the ammo. was some pretty stout Cor-Bon - the recoil was very sharp.