Again... not a genius but I've designed a few phono amps. Lundahl make nice MC transformers, they also have quite a bit of technical info on their website. There is also this handy tech note that provides guidance on setting up the input impedance when used with an MM stage.
If I remember correctly the data sheets for the trafos are missing some information to do the calculation for yourself but I can probably dig out a spreadsheet I've used for the calculations in the past if you can't find what you're looking for in the tech note.
If I remember correctly the data sheets for the trafos are missing some information to do the calculation for yourself but I can probably dig out a spreadsheet I've used for the calculations in the past if you can't find what you're looking for in the tech note.