deepfat

Phil I wish you or should I say your chosen sacrificial mechanic luck, I agree with the wiring comments above, that bracing salt laden sea air on the trip over probably didn't help.
I suspect your car will be the centre of some attention being such a rarity, maybe you should run off some handbills (USA speak?) giving a short history of the MGF together with relevant facts and figures either that or invest in some throat pastilles.
Good luck your now a pioneer
PS in the unlikely event it breaks down either A] throw a tarp over it or B] stick BMW badges on it

Set the snorkel in some non setting mastic if poss, I used gutter sealant it does harden off but silicon can make it a bugger to get off if you need to.

Re the PRT there is probably a from vin no??? on Dieter's site (www-mgfcar-de) but that won't really help as a lot of earlier cars had them fitted as an upgrade later on, I've also read that some people also fitted them in different locations. The answer would appear to be download a picture of the PRT and do a visual check on your pipework, happy hunting.

Those compression figs look good to me, so carry on checking thru the cooling system and you should be good to go, will you still break it or sell complete? SPQR but then no bank of spares decisions decisions.
Re the jiggle valve this might help http://www.mgfcar.de/bleed/ scroll down it's comes after the bit about bleeding and has a piture showing location click on it and its position is clear.
I've also attached a schematic (I presume correct) of the F cooling system which might help it shows 2 jiggle valves that both vent to the expansion tank so 1 or maybe both could be the problem. As stated before read up on the threads but it's awkward as most people (like me) do not fully understand the cooling system, hence it must be the HG.

Maybe Airportable and Notanumber could post jointly as Steptoe-and-Son ?

I presume you mean constantly circulating by looking in the expansion tank Y/N?, if yes it could be the jiggle valve is stuck or has been disabled by a PO. The valve is there to enable any trapped air to vent via the expansion tank but normally not water, a stuck or disabled valve will allow water to flow conatantly thru the small pipe on the side of the expansion tank and show as agitation in the tank. There are lots of threads on the jiggle valves some say they are needed some say not, personally I err on the side of caution MGR did not spend enough on R & D but they still spent a lot and most things are there for a reason.
I'm only into my 3rd year of TF ownership so not an expert but my experience so far is some people will diagnose a flat tyre as a HG failure, I would be very interested to know the results of your compression test as HGF is it seems always the 1st port of call.
Good luck hopefully you'll end up with an engine as a spare or one you can pass on.

Is it possibly your passenger screaming in fear!

If anyone (like me) is wondering what I posted it was meant to be a link it does work if you click on it, it will take you to the item on ebay. Luck or skill on my part you decide!!!!!!!!!!!!!!