An update for anybody following:

With Hymey and Swingtan's insite that the stomp gas was heavily dependent on the MAF we came up with a workaround. The assumption is the accelerator pump fuel at tip in is not available for modification. Whatever default value it is working from MAFless is incompatible with a scaled tune. E67 MAFless, Boosted, Manual trans, Scaled injectors=impossible.

So we picked up an adjustable, boost referenced fuel pressure regulator and dialed the pressure back to 3-bar. This got the 60lb injectors just under the table limit and I was able to unscale the tune. Like magic, you can now mash the go pedal.

Working on the coast down idle dipping too low (getting better) and re-dialing in the VE. Car owner is eager to get the cams turned back on, but I want the VE closer. Car is still in open loop with VVT set to 0.