Enormous amount of work no problem,

20 years ago I converted a 80's Ford escort ( front drive ) to mid engine rear drive. ( think Ford Fiesta Shogun, Renault R5 Turbo 2.

A few years later bought a then 20 year Formula Ford ( Indy car looking racer ) that hadn't won a race in 15 years, cut the entire front suspension off to cure past ills and did total apart rebuild of the car. It then won first race out.

Throw in a Porsche 914 made mostly of MIG welding wire and a oval track car or two just to fill the garage.

I recently got a hold of a 300SL that is going to be converted to a gutted / caged but still street legal track day car. I'm hoping to get sub 3,500 LB ( from 4,100 )

The real question is at what power level will AWD be helpful. The motor will be a M104 3.2 straight 6 with some sort of forced induction as that is the quickest way to more power. Custom cams for these motors are $$ and being they are cam over valve, profiles are geometry limited. 320 HP ( + 100 hp ) can be had with low presure turbos , someone on the performance section of this site is getting 400 ish hp.

Why a 6? I can buy 100K mile 3.2 motors all day for $ 500 where the V8 is much less common and $.