I followed the plans for my XL and found the 36" length too short. 5'9" avg. build. When sitting in the seat I felt like I was sliding forward. I added an additional 6". Now I feel like I'm more settled in a "sling." It's very comfortable. Plenty of room above the torque tube. Matter of fact, I wish I added 7". Also, it would have been easier to go long and shorten the seat rather then having to lengthen it after finishing it. The width is ok.
Do you have any grease plates for the wheels to see how much gear movement happens with you and the engine?Wayne