You can do anything, with sufficient application of a welder and a plasma cutter.
But making a 4WD 914 would be a cast-iron bitch. Note where the transmission is--in the back. Note what is in the way of anything going from the transmission to the front wheels--the engine, and for that matter the whole freaking car... Not a job I'd wish on anyone.
Hey, wait... SammyG--"You can't make an AWD 914!"
Heh, now Sammy will build it!
If he's not too busy being a Concours Weenie....
--DD