B44 VS needs new rear chain

[Mike40M]

I found the rear chain on my Victor Special was uneven stretched. Worst I've ever seen.
What do you suggest is the best replacement?
Go for an unsealed (open) chain as per original. Most efficient transmitting power to the rear wheel, but quite a lot of maintenance. Uses it on my Norton, Honda and Yamaha race bikes.
Or a modern O-ring or X-ring chain. Easier maintenance. But some are wider, problem on the roadgoing Norton, grinding on inside of the primary chaincase. Don't know if it's more space on the BSA, anybody knows?