I've fitted an ST3 motor in my 1994 Superlight. Brought a damaged ST3 and used the engine, wiring harness, clocks. Still a few things to do to finish off. But very happy with the results .
Your could use an ST2 or 3 motor. As for using the 900IE wiring harness?? It won't have the sensors for the water temp. I have altered the ST3 wiring harness to fit my Superlight.
Yep theres some pics on here of the bike with the 944 kit and monster oil lines. With the ST3 engine I have fitted a modded oil cooler in the head light fairing with new black n stainless lines. The radiatior expansion tank sits in there as well as the reg/rectifier.
Loom wise I have extended the positive & negative lines to under the seat to the PC310 & Power commander. Also extended main loom to the headlight loom (which I need to shorten, just to get the connecting plug in the right place and not foul anything) Changed for the main beam,indicators,ignition key. Was a major pain the arse. Still need to tidy up some of the soldered connections - winter job.
Gonna stick some more upto date pics on next week. The Superlight now has 12v Plug (For smoking jacket,gps - the bike even has hazards )
Overall the work is paying off the ST3 motor is a blinder!!! The Superlight Flieees!!
Whats your plans??