Tom, which Land Rover engine are you fitting, is it a 2 1/4, or a 200tdi???
If you don't get fixed up with a clutch plate, I have had good service from Joblot Motors in queens village New York,(no relation) they list a 9 inch (91A-7550) and 10 inch plate (29A-7550) that will fit your splines, both at $39.95, but no 91/2 inch.
If you are fitting a 2 1/4 diesel, I would think the 9 inch would be fine, but you may need the full 91/2 inch for a 200tdi, it may be possible to trim the 10 inch one down to 91/2, if you know someone with a big lathe.
How are you aligning the gearbox to the engine???
cheers Nedsmith