Lots of questions there...
The best carb replacement I have worked with so far for MPG's (and seat-of-the-pants response) has been the Harley conversion. But you have to buy the remachined intake to make it work right. The first kit I used was a complete bolt-on from Petroworks.
You can get complete (long block) replacement engines from John's Foreign Engines, they are pricey but very reliable.
G13b.com
If you can't find a factory service manual in original (print) form, you can download it from
.:Suzuki Download Archive:.
