Starter choices

I would not buy a mail order starter unless someone "Mopar" like Mancini, etc. My understanding is that these mini starters have at least 3 manufacturers, and on B/RB engines CAN have some interference
Some mini starters can be "clocked" (the motor housing) and some not
Some have different electrical terminals, and some have an removeable electrical adapter that helps to alleviate interference.

I've even read that some have done "some block grinding" to clear a boss.

I would go down to whatever, NAPA, Oh'Reallys, etc and get a physical starter to at least try and go from there.