legrandfromage - yes, the tubing is definitely Reynolds, and I checked the Saracen archives and it's 531 which is good news.
andyz - you're right, the bike should be kept original. Particularly after meeting the original owner who gave me the receipt, he'd looked after it well and it seems wrong to respray it as I'd originally planned.
Now had new spokes put on and all going well. Stem is high though! Managed to find an old sample pump from the old Saracen warehouse which fits perfectly so that's now on the bike.
As I'm not keen on red I'm going to sell the bike so it'll be in the for sale forum soon