The Dr. Z 6545 would be an excellent amp to clone as 1) it won't be going back into production, 2)production was ended due to cost, and 3)the thing sounds totally unique and wonderfully thick!

This is my suggestion.  Anyone care to second the nomination?

It should be noted for the record that the original version of the AC-15 used an EF-86, but that was changed in subsequent production after a redesign.
If that isn't the model its heritage stems from then I'm outta ideas.  Maybe we'll get some enlightenment....