Help me complete my build.

I think if it was me, and you're going thru all the rear suspension anyway, I'd be ditching that 8 3/4. You're beyond it performance wise and weight wise. Time for a new Dana 60 witha set of 4.30s. As for the transmission, the 904 combo is lighter and faster and again, if built from the get-go for real performance, more than capable. That 9.5" is laughable behind that engine...lol. You should be talking to a chassis guy now. Before the suspension and items are picked out. A good chassis guy will want to be a part of all that, and be better at tying it all together wtiht eh cage and structural improvements. Also... what brakes do you have? You will want to address that too if they are factory drums on any wheel. As for fuel systems - I'd go with a cell in the trunk for simplicity's sake and order it with a return line capability. I'd go -12 to the filter and to the pump, -10 from pump for regulator, -10 return line. For pump and regulator - Aeromotive black with the 13212 regulator. This combo will give you all the streetability and is capable of properly feeding 700hp+. You're basically building a car the way you want. If there's a class you want to consistently do well in, you should be building for that class. Otherwise, it's just a bracket car.