Any Electrictabs Boogeyman users? Dual-gain mod question

[Bucksears]

I'm revisiting the Electrictabs Boogeyman (Mesa Mark II emu) pedal, but with additional mods/options onboard.
It has a Gain and Volume control (in addition to a Master Vol).

My question is: if I wanted a 2nd drive control to put on a footswitch (i.e. like having two gain level options), would that be the Gain or Volume that is more effective for that?
I don't have an online link to a schematic at the moment, but wanted to post the question for now.
thx

 

[Bucksears]

Did a little more digging, and there's a recent vid w/Doug West, going over the controls on the IIC+ reissue.
I'm going with dual 'Gain' knobs - sorry for the additional thread.