Can not speak to the 500 yet- just received my Big Horn Armory 22" 500 but have not had time to chrono any loads.
I can speak to the 460 as I have have 22" Ruger #1 and have chronoed a number of loads.
The Hornady 200 factory loads are 2900-2950 fps.
other load can be found here
460 S&W: Velocity / Barrel Length
I should note that the 300 grain load test is a very lite load- it is possible to run those at 1800 fps out of 7.5" gun so a direct extrapolation would but the at around 2400 fps.
I don't have my notes available but believe 325 hard cast was around 2700 fps.
In summary the 460 shoots lighter weight bullets better than 45-70 but once you go past 360 grain the 45-70 starts to perform
better and it is clear winner at 405 weight.
Big Horn might be able to get you some data for their 500 I know they had some independent testing performed.
How manageable they will be out of your TC will be up to you. The rifle barrels lengths are available in all calibers.
There is nothing novelty about any of these cartridges in my experience, the all are very capable hunting cartridges with the right bullet.
Good luck and be safe
Ruggy