I don't know the answer, but I wanted to let you know that your car (especially the motor ) is completely badass and you should be very proud. Lots of people would kill for a car like that.
The old school PT88 with the PTE casted T4 .96 A/R turbine housing, was never offered in DBB.
However, they maybe able to retrofit the GT4788R into the H style cover and T4 turbine housing. You would have to call Precision Turbo direct and talk to them to see what can or can't be done. I'd recommend talking directly to Jim myself. It would be pricey if possible, but I'd recommend you stick with an off the shelf GT4788R and make it fit.