Combo valve or manual prop and resiual valves?

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I installed a 4 wheel disc setup on 51 truck, i have a new combo valve that i need to swap for a disc disc, but my question is , should i use the brass combo valve?( it looks ok and has a bracket to mount under mc, looks stock) or should i get 2 2lb residual valves and a prop valve for the rear, ?

Update, when i look at the wilwood adjustable prop valve, just about everything i read says no residual valves needed if mc is on fire wall,