I have a L36 and after reading posts, seems that a turbo, top swap or L67 and HD tranny are the best options. Modding a L36 wont get you far, unless you add a turbo.
Since I still have a good L36 and tranny, I have been working on visual, suspension, and exhaust mods. When the L67 or turbo is ready to go in, the supporting mods will be in place.
The only engine mods I have are a cold air intake, PowerLog, 160A alternator, ZZP radiator+tranmission cooler, and 180 thermostat.