I had a Roadster, the heat in the footwells was excessive, the gear lever was, sometimes, too hot to touch!
So I lined the cockpit completely with Dynamat
https://dynamateurope.com/The difference was remarkable, both in heat and noise reduction.
We changed to a 2014 Plus 8: the chassis and mechanical side is similar to the Mk 1 Aero 8: there is no noticeable heat soak through the bulkhead or the footwell. BUT there is heat from the hot air under the bonnet that comes in through the heater, especially at low speed in traffic.
It is important that the foam seal strip round the top of the heater box presses tightly on to the under side of the bonnet. I've replaced the foam strip with something more robust (Neoprene foam based). There is no real cure, it is a design flaw of all Morgans, but the amount of heat dumped out by the big BMW V8 makes it more noticeable.
I've considered re-insulating the heater box: the material used by Morgan is effective, but not long lasting.
