I'm responding somewhat out of hand, certainly off the top of my head. Seems in seeing this discussed over time that it is possible to use the 444 case and make a kind of 444/45 from it. This helps to solve the long jump at the chamber, but what I've never been clear on is if the 410-45 Colt barrel is full length rifled or is a smooth bore with a rifled choke tube. The latter of those I could only concieve of as being useless. As to the barrel, Why wouldn't it handle the pressures? The barrel itself is far stronger than any single component, indeed the whole of the Handi lock.
Cetainly not to disuade you of persuing a 454 Casull chambering (a far better endeavor than the 500 SW ever was, wish NEF had done that instead) It strikes me that a 445 SM will do all the 454 Casull would do and doesn't require the hoop jumps a 454 would need. (OK, I'm opinionating now, I realize you didn't ask for this part) I think the idea of bullet choices is far over blown, and I also think that any differences in case sizes and operating pressure differences are also feed for technical arguements, that a well chosen bullet for the application in either cartridge will poke holes in paper, cans, cinder blocks, deer, elk, people, mild steel plates and other assorted objects and targets of opportunity.
Obvioulsy the least expensive way to 454 Casull performance is with a 45-70, but equally obvious is that a 45-70 nor a 445 SM is a 454 Casull. Keep us up to date on your exploration of this, an interesting project as it continues to resurface.