My 408W stroker fits the bill and gets over 27 MPG with 0.63:1 overdrive and 3.55 gears. 1650 RPM,s @ 65 MPH in 5th!!
What I don't understand is how you plan to plug in a 351W if you decide to sell it?? Sounds like a serious re-engineering job to me!!??
Good Luck in whatever you decide to do!! It'll be big time fun either way!!!
Jack