I feel your pain - the pretreatment they put down is the same calcium chloride used for ballast in tractor tires - it will destroy rims around the valve stem, after it east out said valve stem. Actually had that happen on an old Ford 2N just...

The frame pedestal. You will need the bell housing too if both are manuals. Nothing from the FE works with the 300.

New, no. Used, eBay, salvage yards, or parts vehicles for used.

The vans and campers also are the same wheel. Should be good 77-79 for sure.

If a picture would be helpful I can slide under my 88 250 5 speed and get a few.

I'm guessing that it may be as simple as needle and seat - the hard warm starts could be from gas dripping out if the carb due to the seat not sealing. Shine a flashlight in the carb and see if it drips while running. If so, then it likely is...

Sounds very distinctly like it is losing connection at the battery.

Timing seems to be what it needs to be. Is the fuel pressure staying when shut down for extended times? If it bleeds down, that can maybe be the reason for needing to fire on second attempt.

Not really about distribution, more about keeping it from splashing around and causing drag. That's how a windage tray in the pan works anyway, not sure the purpose in the valley, unless perhaps more about temperature control to keep the intake...

I can't say as any of my 360's or 390's had that. It must be a performance pan, perhaps like a windage tray in the intake.