What axles etc for this bobbed frame?

[Cmac]

I picked this frame up in a trade. I have a box full of other parts and the 400 motor.
My first step is to find a donor to get a rolling chassis.
Can anyone help me figure out what year donor to get this chassis rolling? Axles , wheels etc. It is set up for disc brakes it looks like.

 

[Cmac]

The hard tail looks done right. I have found an 81 rolling chassis for 200 bucks just need to make sure it will fit.

 

[Cmac]

Here is the donor I'm looking at.
http://amarillo.craigslist.org/mcy/4937021821.html

 

[Cmac]

Here are the dimensions of the plate and slot.