There shouldn't be any clearance issues. You'll no longer need the tensioner that's inside the timing cover, so you'll just take that out and leave it out.
A double timing chain itself wont give you any more power, it's just stronger to handle the added strain of spinning a bigger cam/stiffer valve springs.
I bought the Hesco single roller chain and it was just a Cloyes #C-3085 chain. It was about 50% heavier looking than the stock chain. (However, I felt like an idiot for paying $120 for a part that I could have ordered for $40 on eBay)