hey, I can't see the vid at work, but I know a ton about the rims that von just linked, as I am building a GS and have searched high and low for these wheels! If you want an 18 inch front in that wheel! GOOD LUCK! You will need it and a deep wallet, becouse if you are lucky enough to find the 18 one in the pot at the end of a rainbow, the leprechaun that has it will not let it go cheap!
There are two different style wheels that are both similar, one set (earlier models) has no cut out in the top of the spokes and the brushed aluminum parts cross at the top, the other (later models) the brushed area does not cross and has a triangular cut out at the top of each spoke. The later ones only come in 19 inch fronts, 18 inch rears, I am not positive on the widths available in those wheels. The earlier ones came in the following sizes. Fronts 18x1.55; 18x1.75; 19x1.75; 19x1.85. Rears 18x1.75; 18x1.85. They cam on various GS models From the 1978-1983 GS400, GS425E, GS450E, GS450L, and maybe a couple more like the GS500's. The later models were from mostly the larger CC bikes so I would think they cam wider too.
The fronts in the 19" are easy to find and cheap, there most have been millions made, the 18's are like gold! Very hard to find and pricey, especially the 18x1.75's. Tires are hard to find in a sporty tire for a 19" inch wheel. Check out my Eileen thread (click it in my sig) and you can read a ton about my wheel and tire journies!
earlier style
http://cgi.ebay.com/ebaymotors/83-SUZUKI-GS-GS450e-FRONT-WHEEL-AND-ROTOR_W0QQcmdZViewItemQQhashZitem35a85c5dbeQQitemZ230457892286QQptZMotorcyclesQ5fPartsQ5fAccessories
Later style
http://cgi.ebay.com/ebaymotors/Dragbike-GS1100-GS-1100-19-Front-Wheel-Vintage-Suzuki_W0QQcmdZViewItemQQhashZitem2a0601ab22QQitemZ180489399074QQptZMotorcyclesQ5fPartsQ5fAccessories
I may can answer more Q's about those wheels, just let me know if I can help!