I remember those kits, "Sonic Choppers" here in Melbourne used to sell them, from memory they were a smaller pitch and diameter than the OEM, probably because they used some industrial chain for the application. They did look cool, but even then, there were better options around. Cheers, Terry. 
I remember that, too: for the guys who didn't want to cut their cases, I suppose....there were double-row 528 and 428 chains and matching sprockets, cut out for 750/500 Hondas.
Tin-tin: I vote for chromed, with recessed centers like Honda sprockets, with the teeth masked off. Just chrome that recessed center circle. You can claim "lower unsprung weight" with steel sprockets that way, too! And, if the holes were shrunk a bit in diameter so another one could be added, the lower-yet weight would make even an better claim.
The loss of 10 lbs. unsprung weight adds an effective 1 HP to the ground, all else being equal. My racing experience really proved this out, too. We drilled sprockets like crazy, cutting the recessed centers thinner, too. Inside the wheel rims, we trimmed off all the chrome and a bit more of the metal, too. The spokes were even individually checked for "how much could be trimmed and still hold onto the spoke nipple", then we'd polish the spokes with emery cloth. We also did other items, like smaller (3.50) tires and the lightest tubes, removing the rim band, drilled holes in the rubber cushions, and in the hub where the rubber stuff was captured, the brake shoe metal parts, the hub itself got turned here and there... Between all of it, we lost nearly 4 lbs from the rear wheel. The first time you accelerated away, you immediately felt it, too.
