i would opt for the 454 casull ! just more versitatly, and the 44 mag would probley not have as high of a resale value or be less desireable if you decided to trade or sell it later for some reason, as most people are looking for the 454 , 475, or 500 WE these days!
i have 3 FA 83 , in 454 casull a 6" with a aimpoint comp, a 7 1/2" with a 2x leupold and a 9" with a 1x4 burris , my favorite is the 6" more portable ,handier, and only looses 50 fps from equivlent loads from the 7 1/2 inch . i can shoot the 6 " with the aimpoint with a 7 min dot better off hand than the 7 1/2 " with the 2 x leupold . if i could find a good minature red dot sight that wiil hold up and have good crisp dots i would put it on the 6" and the aim point on the 7 1/2 " but so far ive tried the tasco optima, j point, and the docter sight , on all the red dot is to bright for accurate shooting as they have self adj dot brightness , i will soon try the pride /fowler red dot sight i hope it will work out! '