there two different types of 914 gearboxes
tailshift and mid-shift.
forget the mid-shift, not worth the effort to do.
I'm told (bud do not ahve actual experience) that the tail shift will work well. you just need to flip the diff (not as easy as it sounds, but is easy enough)
I got a 914 mid shift tranny for peanuts plus shipping, in the end it cost would have cost more to make it work, than it was worth, I ended up buying a complete 901 from a 911.
but hey I got a spare case and a whole lot of parts taking up space in my storage shed.
I'd be tempted to use it in a mid-engined project I'm thinking of, except I'd have to track down all the parts for it and the adaptor would cost more than a different tranny that would bolt right up.
good luck