I have a question. I have a 71 dodge crew cab that has a 440 in it
The starter wants to stay running after it starts? Does that sound more like the starter relay orcthe starter?

Recent purchase and the 440 is suppose to be out of a superbee.

Thx for any help

Any time I had that happen I just had to move either the positive battery cable or the 10 gauge wire around (or further apart). A close enough gap will cause it to arch across one another.

You mean the starter pinion isn't retracting after the engine is running?
The solenoid is either not getting a signal, or the solenoid has failed mechanically to retract.
It's been many years since I've experienced that problem, but I'd tend to bet on the starter solenoid, especially if it was subjected to header heat.
Probably wise to check the electrical circuit from the ignition switch through the starter, though; switch may be the problem.
Too bad you're not closer, I have one or two starters here you could try.