The Jtek barend is the cat's pyjamas.
I like my S-A XRD8(W), but if that old Sirius is a steel frame (and I think it is), then
resetting the OLD to fit a Shimano Nexus SG-8R36 wouldn't be that big of a deal.
I was also thinking that cold setting the frame might be preferred if you'd rather use a Nexus or Alfine. I've done it do a couple of bikes. It's not that hard.
Oh and I have the Jtek shifter as well. I like it and it's made in the U.S.