I still have the box for the oil pressure gauge. The brand is "Autogauge", just like this but with Bar scale instead of Psi.
http://www.autogauge.com.tw/web/products/images/2727SS.jpgThe actual gauge isn't very accurate as I tested it at my workplace (I work as a researcher on the field of hydraulics at a university). The hysteresis was something like 20% or so, but I think that it is mainly caused by the sending unit. Anyway I think it as a idiot light that just looks bit better. It's not the exact numbers I'm looking while driving my car, more like a warning if the needle starts to drop or otherwise behaves odly. I will hook up a mechanical gauge directly to the block when breaking in the engine.
The mounting screw holes on the autogauge are almost dead on to the holes that were for the rivets on the original alt assembly. Only minor filing in sideway direction and on the center hole where the needle comes through was needed to bolt it right up. As for the face plate picture file, I think that I still have it on my computer. I did it with paint shop pro by using the scanned image of the original face plate as a help to get the lines to the right place. I can send it to you if you like, just send me your email by private msg or such.
I also have couple of stickers left (I printed four and used only two, one was for practice) which I can send out to anyone who wants for the price of mailing.