915 transmission alternatives

Hello all
I have a 1978 911sc targa and the 915 transmission is getting a bit tired and is in need of a rebuild. My question is, is there a transmission other than the 915 that will work in my car that may be a bit more reliable eg. less shifting/syncro problems. My thinking is if i have an alternative transmission i will not rebuild the 915.
thanks in advance for your opinions.

If you could find one you could put the newer G50 in it. The last one I saw went for $3000.00 on Rennlist. If you need the name of a great shop that will do a total rebuild for a great price E-mail me. [email protected]. Just take it out and send it to them-a few weeks later its completely redone. Even with shipping it was $1200 less than the local shop.