..I recently scored a 2005 Trek 2300 with 9 speed Ultegra and Bontrager Race Lite X wheels on STW!
Nice mate, Ultegra is top gruppo right?
Just found a couple of 58cm Ribbles on Gumtree
Ultegra is like XT. Dura-ace is equivalent of XTR.
You won't go far wrong with a Ribble. They make some nice steel frames and re-brand Tiawanese alloy frames too as their own brand training/race bikes.
I reckon a 58 should be good for you. I ride a 60 and I'm a bit taller