I think this is seat:::Suzuki VL800 Boulevard 800 VL C50 Front Seat 141438 (Fits: Suzuki Boulevard) ....Back rest frame is off a GL1200 it attaches to modified rack to hold Samsonite luggage rack, back rest pad is off an old shadow. I always raise the back of my shelter enclosure about 1 1/2 so it raises the front of the seat about 1 1/2 to make the seat tilt back a little. (I do this with stock seat also, all it takes is a block of wood and drill two holes to match existing bracket and use longer screws.)
The front of seat that fits over enclosure must be heated a little, and use c-clamps and a piece of wood cut to match curve at back of enclosure, the plastic contours easily with moderate heat gun.
Grind the heck out of plastic bumps under seat, two ELL brackets strategically located under seat, drill two holes in frame to attach seat to Cycle. At the sides of seat about 2 inches of plastic that dips way down must be cut so seat is above the side covers. I am not through yet but I have attached a piece of plastic on right side of tank enclosure, painted black to hide the upsweep of the seat that does not match the look of tank enclosure.
I will use a gell pad on top of seat covered in black faux sheep skin, cut exactly to fit just where I sit.