[Scott65]

I'm gonna say it's "possible" that you could add a GM MAP sensor and be able to output the signal to the vaporworx. Trying to run fixed (closed loop) fuel pressure without at least 2 inputs, preferably rail pressure and MAP, is challenging to keep rock steady (and correct)pressure. If I could find a fuel pump controller that would handle the amp draw and had high enough frequency I'd be using closed loop returnless myself. So I hope you get this sorted and will share the solution.
ETA: it may be possible to "share" the signal from the current MAP sensor. I'd check with the Holley experts on this. I believe some of the aftermarket transmission controllers expect signal sharing. So it is done. i.e. tps signals, and map signals.