PB Blaster is too thin, so I'd squirt some Marvel Mystery oil in each cylinder & let it sit a couple of days. A small bottle is cheap. Even regular 30 weight would probably work. I'd really caution against using a 12 volt battery. It will heat things up real quick like & has the potential to fry your instruments & the old original wiring. You don't want to see smoke! With regard to the external fuel supply, just cut a piece of gasoline tubing 2-3 ft long, disconnect the steel fuel line to the carb then connect the new rubber line to it. Other end goes to the bottom of a clean plastic gas can or other suitable container. If there is an inline fuel filter in place then disconnect there, replace with a new filter then connect your new rubber hose to the inline filter nipple. Don't forget to pour a bit of gas directly in the carb to prime it. I'd turn the engine over a bit with the key in the OFF position first just to get the fluids moving, then I'd turn the key to the ON position & crank with a full choke on. And crank for short periods of time & not in long continuous cycles. Things like your wiring & starter motor will heat up quickly if you're not careful. Everything else you've already done sounds good.
Good luck!
