I would suggest getting it set up with reduced boost and enjoy with a safe 350ish bhp for now (forget your 400/400 and certainly 500bhp) and build your funds until you can afford to remove the lump and get it rebuilt with the correct dish, height and cut outs for your future plans.
As you will kill your T34 if you try to achieve 400.
Get the inlet cam swapped for the BD10 and maybe fit W/S kit and get it mapped and you'll have a very potent toy in your hands.