If you don't need the van to be a van anymore then I would be cutting out the bed and sticking in a v8 from something like an Audi s4, cheap to buy and can turbo later, use the whole Audi front sub frame and suspension etc and just lock off the steering, a guy called Toby did it with a VW Caddy and in std trim it was under 4 to 60 so loads of scope. Imagine an RS4 or other in there.

Word of warning though, don't attempt any of these conversions unless you can finish them with either money or the skills. You need to be able to problem solve a lot to get a v8 running rwd in a car that was designed to be fwd. It is FAR cheaper to add massive power and sticky tyres to your existing car set up and lower drag times. 100 shot of nos and track tyres then throw away most of the interior would go a long way, then use light weight panels where poss.