Prices vary but a new one will be around 3500 (including the brackets) the mounting brackets will probably run aroun 300 to 400. (i'm not in my office as I type this) I think I may have a set of brackets that will work, I'll look for them and if I have them, I'll send you a pM, (they will be a bargain). Is your 254 a newer model with steering on the front axle or older model with steering cylinder mounted alongside the engine?.
Greg is right, the 160 is a little more loader than the 254 needs so be careful with it. when we started, that is all we could fit to the tractor, then Koyker came up with smaller cylinders and eventually the 140 which was a little lighter made and lower cost.
Important consideration: does the used loader have the joystick attached? (value about 450.00 new).