I don’t think it will fit as the Ss model is a stretch model with altered rear seat rails and from what l have seen l would guess that the seat is closer or identical to a Ulysses seat.
The Scg was designed to be a standard XBs model for shorter riders, but some of us like that model for its flick Ability! 
The answer to your needs may be at hand though. The Scg standard seat is identical to a standard XB12s Lightning seat, but has around 3/4 inch less foam under the bum. If a standard Lightning seat is still to low you could try and find a 9SX seat which were the most deep padded, or high. The XB12 TT was also similarly padded as a 9SX or may be the same seat so may fit.
I fitted an XB12 seat to my 9SX as the standard seat was too high for me. I tried an Scg seat on mine but that was a bit too hard as well.
If the 12s or SX seats are still too low for you you could try and swap your SCg for a standard 12s bike, or try and obtain the standard suspension. Some riders may want to do a straight swap, but remember to swap the side stand as well. Buell also made a special ‘contour’ seat which is somewhere between a standard Lightning and an SX seat. This was available for a short time and is very hard to find now.
Deep isn’t it?
Don't go for an XB12STT seat, it is the same length as an XB12SS seat. The XB12S and XB9S and SX seats will work.