Hi Scott. It was me who wrote to you originally - didn't mean to throw a spanner in the works!
The 540P has a little mahogany body with small horns, an angled heel and an 'extra' cutaway on the back right along the bottom curve where your thigh goes. It usually has three toggle switches and S-S-H config but was available in many configs, including a special triple-coil monster! It has a trem cavity. Joe Satriani holds a white one on the front of Not Of This Earth and on the inner sleeve of Surfing. Neck is only 17mm at first fret.
The 440P has a body the same shape as the 540P, but has no trem cavity, a five-way selector switch, and is missing the finer points of the 540P's shaping: the extra cutaway by the bottom curve is gone and the heel is not angled. As far as I am aware, this guitar was never a production model and has to have occured as they were coming up with the 540P. The 440P also has a thicker neck than the 540P.
The 540PII is not important here. Doesn't look like the 540P. It has an immediately identifiable reversed body/headstock and sharktooth inlays. Production model, in the catalog of the time, but still very cool as Nuno will confirm.
Hope this helps. If not, I have pictures.