Graham,
rather than going for overkill with a couple of hundred quid's worth of new bits, wonder if it's worth first having a go at pinning down exactly where the problem lies?
Btw, I'd doubt whether it's the plugs, since you've probably already checked the gaps when you took them out and reset them to 0.6mm.
Even if you haven't yet re-torqued the heads and adjusted the valve clearances ( to 0.25 Exhaust / 0.20 Inlet ), that would have more influence on poor hot starting than on poor damp starting.
Since the problem seems to be related to damp weather, the prime suspects have to be breakdown of the HT leads' insulation or a faulty coil with some damage to the external case.
More often than not, poor damp starting can be the result of 'tracking' near one of the coil's HT posts, which will allow the spark to arc onto the light bar on 2CVs or onto the 'goalpost' on Dyanes & Acadianes.
To check for both of the above possibilities, you'll need nothing more sophisticated than something like this...
< http://cgi.ebay.co.uk/0-5-LITRE-HAND-SP ... 2885wt_834 >
As mentioned recently in a reply to Willami, you don't need to wait for a damp day, but instead start the engine and spray a mist of water along each plug lead and around the coil until you find the spot (or spots) where the engine falters.
ken.
