Hey Cool Steve what are you going to do for a replacement cassette on that proprietary Mavic 571 rear hub? I've never even seen a Mavic shark tooth cassette for sale that wasn't paired with a Mavic hub...

I've been looking for a 36h or 40h 130mm rear Mavic cassette HG compatible cassette hub for a long time. I see Mavic 571/2 hubs come up from time to time but they are always 32 drill. I've heard that you can replace the hub cassette body, but I really doubt that you can use a modern Mavic hub body. Anybody know?

I saw a 40 drill Mavic 501 rear hub on eBay recently but it was a freewheel hub, and I already have a NOS 36h one. I'm not inclined to build it up as I'm currently too heavy for anything freewheel, save a Phil Wood.

Why don't you source some Mavic road drop handlebars for that bike instead of the TT bullhorn bars? They wouldn't be particularly safe (alloy bars shouldn't be used but a handful of years and then retired) though...