OP needs to think what budget he/she has, as a custom ti is going to be at least £1100 f+f, as MacB quotes for his machine (Mac, what's the make? It sounds an awesome bike).
re wheels: I have actually toured on 10 Speed Camapag on Centuar hubs and Open Pro rims, only issue was the rear rim wearing out rather quickly. I have a full custom Yates in 653, I had Dave crank the chainstays so it takes 32mm with guards. It is a customised Wanderer IIRC and handles very well although it has a more agressive postiion than I think is normal for a tourer - probably why it's marketed as a fast audax machine. Changing the wheels has the largest effect on speed and handling: with a set of lightweight wheels it is fast and very lively. Only thing I'd change is the 1" headtube for a 1 1/8" for future fork upgrades/replacement. BTW I don't think fork weight has a huge effect on speed, not as much as wheels anyway.
EDT: A good framebuilder will question you on what type of cycling you want to do and get your position by sitting you on a jig and adjusting it until you are comfortable. Hewitt does this, so does Mr Yates. Then you will get the bike you need, not the one you want.