I would not trust that coupling chain past the garage door (sorry). My little BSA 500 with maybe 40 hp uses a duplex primary chain, and I have broken it, as others have, and I ended up doing somersaults down the front straight at about 60mph because the broken chain wrapped around the clutch and seized the rear wheel. Duplex or preferably triplex, running in oil as a minimum. Changing to larger sprockets of a size that you do not need an idler (spacing at an exact distance) would be safer, as that idler could self destruct in no time. Larger sprockets will increase chain speed, but lessen the tension in the chain as well. Gears would probably be better, but then you'll have to add idlers with shafts with very stiff stub axles (supported inboard and outboard or double bearings inboard). I'm not an expert on these things, but as a retired engineer, I see potential problems.
Tom