Jay McKnight (owner of Magnetic Reference Labs) is a good friend of mine, and I would say "buy the correct tape from him!"
We gotta support the folks who actually help us with things such as analog recorders.
However, if you read:
http://home.flash.net/~mrltapes/choo&u.pdf
...Jay tells you all you need to know in order to use a "wrong" MRL alignment tape.
If you're on a tight budget, I suggest the "short" alignment tape with a chromatic sweep.
Bri