If your already getting ping uphill hooking up the vacuum advance will probably only make it worse and destroy your engine so I don't suggest it now. Although if the carb is real lean that can make it ping. I never noticed you saying it is the MP dist. Like T67 said they already have the quick advance so you don't need to mess with the springs.
It's JMO but that'd be the best $350 you'll spend if you know for sure the dyno operator knows what he's doing. I don't think a 800 Eddy is too big. You don't want to go any bigger though. Is that the Thunder series? If so that's a real good carb. Sounds like it's just running lean by your description. If you get the mixture en-richened to where it should be the ping might go away. Try to get that pinging stopped ASAP cause you can beat the pistons and bearings out of an engine in no time if it's spark knocking. I've seen it happen in 150 miles.