throttle control aassembly for scarab 300
 

I'm looking for a replacement throttle control assembly for my 77 scarab 300. Does anyone know where I can find one? I thought about converting to a 4 lever style, any suggestions on brand or model number?

I have TRS drives and they shift electronically. Most of what I have found shifts with a cable. Any suggestions?
Here's some photos of what I've got.

http://s17.postimg.org/z71bdibxb/20150506_200358.jpg
img hosting
http://s3.postimg.org/fetydjw4z/20150506_200329.jpg
jpg images
http://s13.postimg.org/c220zt6c7/20150506_200311.jpg
upload a picture
Ignore the horibe wiring the boat is under construction!