I most definitely WOULD NOT , REPEAT NOT load or shoot any of the 405gr .458" bullets through your Taurus Thunderer.
I don't know exactly what level of pressures the steel will take, but the design was for black-powder level loads and the locking mechanisim probably won't take much more than Black Powder equivalent loads.
But, thats not a condemnation of the gun.....
A friend of mine has one, and weve shot a LOT of handloads through it, and he killed a doe with it this past December. The rifle is decently accurate, and a joy and thrill to shoot. I even got complained on by a "difficult" neighbor for shooting a machine gun. We were running "speed drills" with the Taurus and dumping 10rds in about 3 seconds. Load is 7.8gr of Universal under a Lee 255gr FRN at .452" with SPG lube.
The heaviest load I'd try through it would be a 300-315gr with a crimp groove for the SAA type revolvers. There's plenty of data in the manuals for such loads, so I won't go there....
In theory, the 405's might work, but in reality, the velocity would probably be around 500-600fps, and would require to be sized down to fit the chamber, and would also be too long to feed unless a different groove was cut or turned into it. Besides that, the accuracy I've gotten from Lee 340gr .458" bullets I sized down to .452 rendered the excercise moot.... Accuracy was non-existant.... A non-sized bullet probably would buldge the case to where it wouldn't chamber anyhow...
The 255gr FN's work superlative on deer at the 1,150-1,250fps you'll get from the Taurus, and will shoot clean through most any deer at most any angle. Enough, really !!!!
Enjoy your rifle.
If you want/need a .45/70, you can get a good used Marlin 1895 for about what your Hospital will want for a deductible on your health insurance claim after you blow up your Taurus..........