A 1" road bike headset might do!!
And maybe some of the Burner Boys might know of where to get them.
Most Raleigh bikes would have used the smaller headset (Not the BMX's though, I think)
You'll have to do some searching on Ebay or internet and then email them to find out the cup size diameter!
What is the internal diameter measurement of your headtube?
PS. Its still a 1" headset just different sized cups!!