Ticking at idle, that's not generally an octane problem because compression pressures are very low with the throttle closed. You will get some noise transmitted through a cylinder every time it fires, power valves tend to make some noise too. It's really hard to make any judgements without actually hearing it. If it didn't click before the rebuild and did afterwards, I would be concerend. It never hurts to pull the pipe and carb/reeds and take a look inside to see if everything is wearing in properly and make sure no wrist pin clips popped out.