"But I have yet to pull things apart and grab my alignment tools/gauges out from under my workbench wherever they are..."

That would be a good first step; since you have the tools you may as well use them. Did you size the new chain properly? Did you readjust the B-screw to accomodate your smaller big cog? Did you thread the chain through the rear derailleur correctly? (We've all done it wrong at least once.) Did you remove any un-needed cog spacers and are all of the required ones present? There must be something basic wrong, friction shifters should cover a multitude of sins.