I have built two TF P-51 and the P-47 all with OS 120. Each has been mounted inverted with on board glow. The onboard glow is just a personal preference, ease to start, better idle etc. The P-47 has the 120111 pumped version the P-51's are the nonpumped. IMO the pump is of no real value and it can give you fits, costs more,adds weight, no increase in power that I can tell. The OS 120 nonpumped are great and I would highly recommend them for the P-51. I turn a 16-8 and the plane just hauls AS_ !!! Its a perfect fit.