Hey, that's a pretty ballsy route, and if you do it, I want to read your report.

I've never ridden most of those roads, but I've driven a lot of them. You'll be going through parts of Philadelphia that I would prefer not to go through; the streets are bad, there are trolley tracks (not to mention trolleys), double-parked cars, and a lot of urban blight. Nothing to be afraid of, exactly, but I would find it distinctly unpleasant.

My preference --disregarding the bicycles-- would be head west to Lambertville, then drop down a bit, pass through Coatesville , Parkesburg, Quarryville, and cross the Sesquehanna at Holtwood, then head south. I haven't ridden most of that route either, but again, I've seen a lot of it from the car, and to my mind it would be way nicer than what you're suggesting.

But maybe that's just me... good luck!