I run a 500 Weslake in a featherbed and a 500 Weslake in my sidecar. Both knock out around 60 HP. Some years ago I bought a 10' strand of 1/2" industrial chain and used it on the Norton. El Mirage is 1.3 miles to the lights. The industrial crap would last one run and it was done. It would stretch and have a number of tight spots. It was around a 1$ a foot.
A couple of years ago I bought the top of the line D.I.D. chain for the sidecar. It ran for two seasons of El Mirage and two Bonneville SpeedWeek meets. Netting six records on the way. And it was still good after all that abuse. I changed it out for this year not because it was shot but just as a preventitive maintenance sort of thing.
As I said earlier, Tony nailed it. DON'T try to cheap out with some crappy industrial chain. Or if you do cut several lengths to carry with you. You'll probably need them.