Thanks for all the replies everyone, much appreciated.
You've answered the question, which is that I should get centre-pulls. The rear brake cable bridge is really nicely done, so you're right, I should therefore use it. I've got my eye on some Mafacs right now.
I'm sticking with 700c wheels mainly because I'm running 8spd Record on this bike, and already have a NOS Record cassette installed on my Aksiums (they are officially the only new wheels that will take an old Campag Record 8spd Exadrive cassette). I'll eventually shod some nice 28mm tyres and proper mudguards on it, so that'll soon eat up any clearance !
Thanks for the comments about the frame. It was an impulse purchase off eBay, partly because I liked the colour. I was rather pleased when it arrived in the post to find a newly installed Record headset, 531c tubing throughout (not 'plain' 531 as advertised), Prugnant arrow lugs, double eyelet Campag dropouts front and back, brazed 'noodle' cable guides *under* the BB. And my 130mm rear wheel just slotted in. I actually think it might be recent enough that it's post-126mm. So I'm not sure that it was designed for 27" wheels.
There's no model or branding, just a Willi Moore sticker on the top tube. I'll try and find out who made it, possibly Harry Quinn or someone in the NW. Some of the older members in my club knew Willi a few years back, so I might actually just ride over to Merseyside and ask the man himself !
Any as you've noticed, it seems to have been built to order for someone who wanted to do touring with a rear dynamo, yet have a lightweight frame. It's all perfect for what I want, so I'm rather pleased - buying things on impulse can be good. Oh, and I got the frame cheap too.
Anyway, once it's on the road, I'll post a new topic so that I can show it off, as I think it's possibly unique ?