..OK, so much for "don't they just pop out..."
Made a tool to hold the camwheel so I could undo the big nut. No problem. Nut off, cam bearing caps removed, cam going nowhere. Risked tapping the camwheel to try and encourage it to move. No go. OK, make a tool out of some 5mm plate and a 7/16 UNF nut plate & HT bolt to press the cam out the back...after much hassle, rear cam popped out....but broke the tool (stripped the thread out of the nut plate). Repaired it, front cam came out as well...but both VERY tight.
Once cams out, found 3 very badly worn exhaust cam followers (pitted like crazy and a dish at least 1mm deep). 2 at the back, one at the front. All inlets perfect, other 3 exhausts only showing very slight signs of wear.
I fitted the replacement cams and the best 3 replacement followers I had (fortunately, there were 3 good ones).
I ran out of time at this point so still have to set the exhaust gaps and re-check the inlets, then put the tops ect back on....and that flippin' cambelt cover in all it's myriad little pieces.
Lets hope it sounds less like a box of spanners after all this...
...and finally....I now have a pair of used cams. Don't know it they would be suitable for a re-grind or not to be honest. Obviously, 3 exhaust lobes are not in good order. Anyone interested in them?