Hi Jorsan, the Tape Project tapes require a 15 inch per second tape speed and a 1/2 track stereo head format. If you haven't already bought the A77, you might think about getting a B77 instead. I had an A77 back in the 70's and loved it, but overall, I think the B77 is a better machine and most of them will be a decade newer too. When your talking about the precise mechanical aspects of these machines, age really makes a big difference. Here's a link to a modification thread that Arian Jansen developed. Even if you do already have an A77, this should give you as good a guide to adapting Arian's mods to your machine.
BTW Welcome to the forum.