I am now ready to confirm the 3rd option
I bought the OBP fuel scavenge tank from Pegasus and it worked great. 90 mins of tracktime without a burp, bobble, or hesitation.
It was the perfect solution for me as I had both low and high pressure pumps on hand, and several cells, all good, but without access plates. I also had room (because it was a tweener) for the bulky tank. However, I still recommend that people doing a conversion rebuild their cell and install the pump in the cell with a baffle system. The external pump with in cell baffle system is second option. If you use an external pump with a standard fuel cell (as used with Kent or Pinto) then you will absolutely have issues with fuel pickup. Guaranteed!
The engine conversion is everything I hoped for. Refuelled between sessions. Torqued the wheels. Adjusted tire pressures and shocks. Then went on track again. Now I can concentrate on driver development and chassis setup. Hope to see others make the plunge and keep the class viable going forward.