Most guys with twin engine cars run 2 pedals next to eachother. Possibly with enough room that you could 2 foot it if you wanted.

Expect well less than 450whp out of the 5830 turbo. A 6262 is almost a 500whp on race gas and big boost numbers.

I would expect some solid low 10s even out of a small trans build with just the rear engine.. the front engine may not be help you run much faster at a dragstrip unless you set that up with an even bigger turbo than the rear has....