The solenoid does not turn the engine. The starter motor does. The solenoid does act as a high current switch for the starter motor. If switched current is excessive (starter binding from heat or dried out lube) then the contacts from the starter to the solenoid can burn out. Therefore the starter won't turn via the factory solenoid.

The remote solenoid only provides a new starter on/off switch. The original solenoid still provides the true solenoid operation...sending the Bendix forward to engage the starter.

The remote solenoid is not a fix, it is a work-around.

I have Hedman 4 tube Hedders on a '68 Firebird 400 and there is adequate room to easily remove and reinstall the stock starter.