It was a choice between DTSwiss 180 and 240 hubs. The 180 required centre lock whereas 240 can use 6 bolt. I had a think about it last night and in reality I'm splitting hairs as both are excellent hubs. I think I'm going to go back to the original plan and get 2 6 bolt wheels based on the 240 hubs. I am trying to avoid the potential need to file welds on a new frame.
I can't believe how much confusion I am managing to generate for myself
Once I get the build done I will try to post a summary of everything I have learned on this thread with the help of all you excellent forumers so if any other clueless newbie comes along, it might save them (and you) a bundle of explanations.