What fuel is best?

So the things that may cause it to ping on the trip will be carbon buildup on the residue and too much timing.
The most likely scenarios for timing a little bit more advanced are a) someone set the initial too high b) springs have slightly stretched.
I wouldn't worry about either really. Start with a with a name brand mid octane fuel, and if you hear a slight ping or rattle at part throttle loads (uphills), then back off the throttle a hair and next fuel up use a higher octane. If no ping, you can try a regular (87 AKI) next fuel up.

Sunoco's main east coast facility for high octane pump gas is out of commission since the fire. I don't know what they've been doing but it seems to me their retail prices for higher octane are reflecting that shortage. Just my limited observation. Conoco and some others don't seem to be effected.