New engine/transmission start up

Lifted many engines/transmission with a carb plate. As long as the threads are good in your intake, not an issue. One of those bolts/studs can hold up the ENTIRE engine/trans.

If you have a mechanical fuel pump. Go to your local pharmacy and get a kids liquid medicine syringe. You can fill the carb through the vent tube to get fuel in there. You don't want the engine cranking to fill the bowls.

Throttle position linkage to trans doesn't matter as you correctly noted, no load.