I have a 629 and I would really like to make a competition gun out of it. Would I be better off selling it and buying 625 or other? thanks for any help you can give.

Just curious, AZGUNNER, did you ever try .44 special loads from that 629?
That may save you any loss in a trade or the cost of the parts to convert it over.
By the time you aquire a .45 barrel and cylinder and installation costs, you may be better off trading, IMO.

Sure it can be done but at a cost of 2 new S&W revolvers in the calibers you are requesting.  To get a custom barrel and cylinder and the labor, the labor is the real killer here. Just buy a S&W model 610 or a 625. The 610 is a 10mm but will shoot .40 S&W and the 625 is a 45ACP.  Trade or sell your 44mag or keep it and shoot 44Spl in it and own 3 great guns. If however you are still interested in converting your 44 give me a call and we can work something out.
Jim
Miossi Gun Works
319 465-1911