As for the Hillman 'Pimp', that might prove interesting, providing you keep the head true! 
No worries, not vexed, just get frustrated by all the laws which pretend to be about safety but which will have no effect whatsoever on safety
Imp heads are easy - use coolant.
That's it! Back in the day, when they were brought out, only exotica used alloy engines (ignoring aircooled bikes!), so everyone put antifreeze in the cooling system in the winter and water in the summer... fine in a big old iron block... but without the corrosion inhibitors alloy furs up, the fur sweeps round to the thin pipework of the radiator and then stops!
Now the cooling is ok, just(!) An standard Imp with a half reasonable condition cooling system will run a little hot if you hold a steady 70-75 on the motorway (not far off top whack!) and is fine everywhere else (we've done 400+ miles fully loaded at 60-70mph with no probs), if the radiator is choked however
, now if you take Joe Bloggs, he will try to continue driving his overheating Imp until it stops, by which time the head is probably warped
and of course it's not his fault for abusing/misusing it.. it's obviously the fault of the car..
On racing Imps they mostly fitted a front rad, and on high comp engines wills rings are the accepted mod, but the cooling system really is ok if you treat it properly, and the engine is a little gem
they used to be popular with hydroplane racers because you could run them up to 10,000rpm and they would hold together for several races before needing precautionary rebuilds. Little else would at that time
Of course another attraction is that I could easily put a heater in the chair...
