It would be really tough to do and make it look right/good. You'd really have to do a deal like the SN65 project and even then you'd have to find a car with a similar width floor and wheelbase. I'm not saying it can't be done, but I don't think it can be dine for short of $100k even if you have all the tools and knowledge. I thing SN65 said they'd be well over $100k once they were done when you consider the labor involved. The easiest way is via the 4x4 route, but I don't think that's what your looking for. My '94 LHS that I bought for $50 has a V6 that is mounted like my V8 in my '65, but the tranny mounts to the rear and wraps up under the pan and uses half shafts to the front end. Similar to the old Olds Toronado. Now if you were to somehow modify that tranny and tap out the rear with a driveshaft, that might work, but I think the actual tranny happens after the thing changes directions, so it might not work. The problem with just about all the AWD systems out there is that none of them, to my knowledge, will mate up to a SBF without major mods, and then most probably won't survive. Those that would survive are most likely rear engined vehicles. Maybe you could take a Porsche AWD drivetrain and use a driveshaft going back to the tranny ala the new Corvette. It'd help your weight bias if nothing else.