Wow, that is just unreal. As a guy who happens to own 2 '05 VNL64T300s (one ISX, one D12)...this is so up my alley it's not even funny. I didn't even know a VT42anything even existed. Not to mention the fact of an Allison in it. I know it's all factory scrap one-off junk, but being that I tried very hard to get a VNL/VT single axle (with a liftable pusher) with an Allison built (Volvo's engineering dept said "NO", LOL), this really piques my interest.
I assume it's a D16, yes? I know they offer a D16-700 across the pond, and I almost bought an early '07 625, but they were just so heavy I couldn't do it (ie: a 16K lb 4x2,,,LOL!). I know the Volvo on-highway engines are tuned down significantly, based on what Penta motors can do. I've only seen one or two instances of Volvo motors/ECUs being played with. It would be pretty neat to learn the ins and outs of the Volvo motor, if a real knowledge base existed outside of the narrow OEM stuff dealers have access to.
Looking forward to what you accomplish next!