What's the best way around Pittsburg? North or South of it.
Depends on your goals. I70 will get you past it in a hurry and offers decent riding for an e-way. I76 will get you past it on the north but I have no idea what it's like. There's some great riding way north on the other side of I80 -- but that takes you through some of the worst of Ohio and quite a ways from Gettysburg.
If you're taking US250 as recommended above, you can probably piece together a nice route -- maybe along US40.
If not, staying north might suit you better. US highways don't run east-west through there so you'd have to piece together a route using state roads. Done that a couple of times and was generally pleased with results. I think I've done PA65 and PA108. Maybe it was PA588 and PA68. Or PA228. Not really sure. I've got GPS tracks somewhere but can't tie memories of the roads to them anymore. That part of PA has never been a destination for me.