Well, I took the plunge today.......
Front inlet cam removed, two shims out and measured - luckily the RHS shim was just right to correct the LHS so I just needed to buy one shim - a bit pricey at £6.25 from the local Stealer but they had the right size in stock so I'll let them off
Swapped the OE CCT for one of Bazza's and set it fingertight then back 1/4 turn. Hope this is correct, will find out when I start her up - eventually.
Then found TDC on the rear cylinder then swapped that CCT.
Job's a good'n.......I hope.
Thanks for all the advice.