I believe SIMUN means some sort of desert wind. ' Vento' means wind 'caldo' means hot.
Here some photo's of the seat making process.
The base of the MK1 or MK2 seat works just fine, and then extend the front with polyester mats and adjust the steel frame to the right hight/ level (with a lot of rings and damping rubber in my case). I think i also welded a bit on/ of the steel frame of the seat, now i am thinking of it.
Shame i did not make a photo of the bottem side, but i can make one if you are interested of course.
Original 'fat' Mk3 seat (to long @ the back in order to fit it passes the rear rack when you take it off):
Slimmer Mk2 seat shortened at the back and extended up front:
