Hi Tom:
Yeah...if the A80 has the heavy full side plates, it's a VU model more than likely. You can also identify its model by locating the Rec and Repro adjustments on the meter bridge. The seller should be able to see the actual model number and serial number in the back with run-time hour meter that will give you pretty good idea on useage life of the recorder. Let me know if you need further info on where to look. It would be best to get the Mk II at least.
There are opinions that VU models' factory audio electronics are not as audiophile quality as the RC model due to heavy use of now obsolete Philips TDA941 opamps in Rec, Repro and in the VU meter amp sections. The RC models have very straight discrete audio sections that are simple in comparison to VU models. This clearn audio configuration may have been the main reason why Mark Levinson picked the RC model over the VU model to make his legendary ML5 recorders.
Due to its simplicity, the RC model is not very flexible when it comes to EQ selections. You basically have to decide on the EQ and not change (other than having different sets of audio cards for NAB and CCIR EQs and swapping the cards...). The VU model's EQ is selectable from the meter bridge.
On the other hand, if you plan to use an external tape preamp such as the Tube Repro Preamp for TP tapes, VU model is ready for action without the mods. The heads are wired to multipin connetors that can be plugged into other devices. You can configure the record section to be factory state but re-direct the repro head connectors to the external tape preamp.