Here below are some reference pictures of a genuine, original seat from a 750 S3 from 1975. All the original seats for the V7 Sport, 750S and S3 models were produced with metal bases. Nowadays, lots of Guzzi 750 seats appear on Ebay in various condition, but if you want an original one, it has to have a metal base. Seats for these models have been reproduced the last 10 years or so by Stucchi in Mandello, and they have a plastic base which is in fact far more practical and sensible. However, the plastic bases can crack easily (as I found out when someone crashed my S3) and I think the fit is never particularly good with the repro seats. The repro 'monoposto' or 'einmann' or bumstop' seats for the 750S and S3 never seem to have the right lines compared to the original, in my opinion.
A company called GAMAN of Milano manufactured the seats for Guzzi. They also made very tight leathers as you can see from this ad, also featuring a nice V7 Sport:
The original seats were made with a combination of a moulded 'stitch' for the panels or stripes on the actual bit where you sit, and other panels which were then stitched onto this main moulded panel. The whole cover was then heat pressed onto the foam on the meatl base, and then glued underneath. Although the stitches appear white, the Italian expert who recovered my other original Gaman seat base told me they were originally in black thread, and the colour just fades out from the thread over the years and becomes white.
The V7 Sport seat was a genuine dual seat, with the 'Moto Guzzi' logo printed on the back. The 750S and and S3 had the fantastic looking but impractical race style seat.
Although it's nice to have an original seat, don't pay too much for rubbish. The metal bases are by now between 30 and 35 years old, and they rust easily. My original seat for my S3 broke in two pieces back in 1991, and I threw it away as it was impossible to weld. If you find an original seat, you may be able to get rd of the rust and repaint, but it's likely it will need recovering anyway.
A seat recently went for £132 on UK Ebay, and it was advertised as needing complete restoration. In my opinion this is far too much, I'd prefer a repro seat at £115!!
Here below is my original seat. It is missing the passenger strap that came on these seats, as I have put it on the recovered seat on my S3. This seat is good enough to use on my bike, although the plastic 'chromed' strip is not nice and the base would need respraying.