The head is off - over with Danny from MX5 Plus to get crack tested, pressure tested, machined and rebuilt. I spent a couple of hours this arvo with an emery wheel and the dremel, and some 1200 grit wet and dry, cleaning off casting ridges and smoothing off the general roughness from the intake and exhaust ports.
The thermostat appears ok - but it is yet to be temp tested.
The head gasket wasn't cracked, but that's not to say that it hadn't sprung a small exhaust-coolant leak which sparked my overheating.
Cracking the head gives me a good chance to see how the piston faces look. A little bit of carbon - nothing that a bit of a cleanup won't fix - no water this time.
Will be interesting to see how she performs when the head comes back all nice and clean. Could be a GRAND excuse for a bit of a dodgy day to put it all back together - probably not all this weekend as I doubt the gasket kit will have made it from the UK, but certainly the Saturday after.
Who's in for beer and cars?
Sounds like you were waiting for an excuse to get the head worked!! 
