I have rebuild the 57 Lincoln premier motor & picked up a Holley EFI kit. I'm trying to find the right alternator to swap out the generator but I haven't had any luck finding any information about what works on this motor

 

This isn't an FE, but rather a Lincoln Y-block. You might be on your own for this one.

 

I think that your best bet will be to get a little bit creative and make a bracket to fit a common alternator. I would use the older GM internal regulator style. You can even buy those which have been modified to be self exciting and only need one wire.

A nice feature of these alternators is that you can get a pulley for almost any imaginable application. Places like Speedway sell them that will even fit the large belts like used on a Ford or Ferguson tractor.