You can probably find one, but it is more likely to be for a 420 size chain or larger. Various off-road go-karts and motorcycles are likely to use this larger size. They may also be available in aluminum to keep the weight down. You can also use an intermediate shaft with more sprockets if gearing down is what you want to do.
Try Azusa Engineering. They list up to 100 tooth sprockets in #35(hthttp://www.azusaeng.com/azusaline.html). Here's a 1-piece 72 tooth aluminum sprocket for #35:
http://www.mfgsupply.com/m/c/AZT5313...ml?id=gDhaXDzL
Possibly try sprocketspecialists.com They list sprockets up to 72 tooth, but you have to fish around by the make of motorcycle.
I believe one of the West Virginia teams used a very large sprocket last year to make a 4WD 4 wheel steering 'bot last year.