Mike C

I'd check the timing with a timing light and see if it moves/disappears during the farts and bangs.

I use petrol or kero to remove the gunk and then blow it clear with compressed air. There's not a huge volume of air flowing through the trap.

If the "PCV" has just wire gauze in it its a flame trap. It's the gauze that needs periodic cleaning.

It's usually in the vent line connected to the side of the cover( looks like the PCV fitted to later cars) and can block.

Pump cavitating or PRV sticking at full bypass?

Is the tank venting properly ? Open the cap and see if things improve. Maybe the run heated the fuel so much it's boiling in the pump suction line. In this case it will improve when the tank cools down. Where is the pressure gauge tapping? The gauge is not showing 108 psi.

OK. Could be heat soak from the block to the coolant -the 10 min delay is a characteristic of this cause-this has happened to me occasionally on 40+C deg days in an old V8 Holden after a few hours running at high speed. These days if this is likely to happen I idle the engine for 5 mins or so after stopping to cool things down.

Forget the coolant colour. I'd check the coolant foam for combustion gases, in Australia a test kit for these gases is around $50.

If you rev the engine with the radiator cap off, radiator full of coolant, do you see bubbles appear?

Whatever your decision, you may want to consider that most TR tyres these days age expire long before they're worn out.