Options on converting away from the cotter pin cranks on bsa wayfarer bicycle The shell diameter I just measured it at 70mm but am unsure about the threading. 

However considering both the fixed and adjustable cups needed a hcw11 to remove, am told it's likely it uses raleigh proprietary threading.

Some guidence on what am  looking for will be greatly appriciated

If possible converting to hollow tech II will be ideal as I already have an MTB  using that BB hence the tools required will be handy to have.
That's probably going to be an issue. Sheldon Brown has this page about BB standards:

https://www.sheldonbrown.com/cribsheet-bottombrackets.html

From that I'm guessing yours is probably 71mm x 1 3/8" X 26 tpi which is not going to be compatible with much of anything. I don't know if someone like Phil Wood makes cups to fit that size.