Can I fit any 1" threaded headset to my Orange E3 frame? I am thinking of going all out with a Chris King - will that work? If not, what's a good alternative? Thanks.
The main two considerations are the forks and your preference.
Are the forks original threaded or threadless? Also stack height will have to be looked at. Some sealed bearing types have generous stack height of 40mm+ and some ritchey ones have a mere 33-34mm. This factor may blow your forks out of the water!
The forks are the original rigid threaded forks that came with the frame. The headset on there originally was a Deore XT, that has now had it. Should I take some measurements?
Ok, yes i would measure up and go for a similar stack headset. I can be a mil or two less but only a mil more.
Personally i'm not sure exactly how to determine stack height as i just have an eye for what works and have a selection of top and bottom halfs to swap out and get it right.
I'm sure somebody will be along to advise on stack height