I have 87mm pistons and a stock TR4 cam. I have a plastic yellow fan (mounted backwards) on the stock extension, as well as an electric fan controlled by a thermostat (but it does not block the crank hole in the radiator). I have 3/8" push rods installed. 5lbs was removed to make my flywheel weigh 14.5lbs. I have a pair of H6S's (not H6's). I have a uprated (DOT5 tolerant) hydrolic T-O bearing in my HVDA 5-speed. I have 195-65-R15 tires mounted on TR6 wheels.
I can dump the clutch without giving gas to pull out, but generally rev a little and feather the clutch to make it smooth. I can rev it up a lot, dump the clutch, and spin the wheels easily. The last time I auto-crossed, I stamped the brake so hard at a hair pin turn, that I killed the engine. I didn't notice until I let off the brake, and noticed the engine had to restart before taking off again. My course times were very good (I was only behind a TR3B and a TR6 -both driven by excellent drivers) -and not by much.
Although I have yet to drive in Texas 'hot' weather, I have not overheated in temperatures around 90.
I am happy so far, but am looking forward to a real test in heat. I drove it to Pa last fall and am planning a longer one later this month. I'll let you-all know how it goes and hope this information is useful.