You might want to put a free "wanted" and on the AOMCI.org website. Someone out there is likely to have what you are looking for....although those racing LUs are usually pricey. Also, you might want to email Bob Grubb (Bob@grubb.com) who is trying to liquidate all of his old Merc parts.
As Wizard was built by Mercury, up to 1957 you look for the Mercury A-B Quicksilver unit. Whether you want to run a 1-1 gear foot or a 16-21 foot, be prepared to pay BIG $$$$$$$$$$ if you can find one, especially if it is rebuilt & the foot has been gone thru, gears, shafts, seals etc. I have seen the 16-21 foots ONLY bring $800. A complete, ready to run quickie $1000-$1500 that is a 1-1, (low price), 16-21, High price. Good luck.