This is a TERRIBLE idea!! Not only is the .454 loaded to dangerous pressures for the Contender frame - have you ever seen the barrel walls on that octagonal barrel? My 15 year-old barrel measures only 0.051" thick at the muzzle, thinner than a shotgun barrel. Regardless of the frame strength issue, I'd worry about splitting the barrel with .454 pressures.
I really like my .45LC octi, and it shoots standard .45LC loads (250@850 fps) surprisingly well. But it is extremely light in weight - with the thin barrel and large hole this isn't surprising - and recoil is "stout" for such light loads. Good for carrying, but you may want to consider rubber grips if you don't have them. Enjoy your new purchase!