All Small Six Electric fuel pump? What do I need?

[DON]

And placed after a partially functioning mechanical pump, it is still pushing fuel, even when high in the engine bay.

And…. I would think after the electric is primed, it would work better than having to have suck gas all the way from the tank

 

[drag-200stang]

Yes, by the tank is good, in tank pump would be best. On some projects it is not worth the time.
I had a solenoid pump that would pull fuel very well.
Even dry, but I do not mean the lines and pump were washed out and blown dry.

 

[Frank]

When fuel issues created by heat or vaporization then the electric pump is better to push into the mechanical pump. In the set up you advise the pump is still likely to have issues from the mechanical pump failure. I have an old fire truck that is set up this way just for that reason and has two electric pumps at the fuel tank and switched so you can run one or the other.

No doubt Cool23, we're not in disagreement here. Fuel being pushed is always 100% better. The OP has the same unusual issue I happened to have, AND he asked specifically about being able to mount the pump under-hood. Yes, if the mechanical pump fails, this set up is not effective.
I have new fuel tank and lines, and the mechanical pump has head pressure from the tank over 1/2 full. There is no vacuum or heat induced vaporization issue, only a 63 year old tired mechanical pump. I snagged the $15 Amazon pump off my lawn tractor and slapped it in as a stop-gap. Safest permanent fix for OP and me: get a rebuilt mechanical pump ($250) or a quality electric mounted at the tank.

 

[Cool23]

No doubt Cool23, we're not in disagreement here.

I could see that........