At the moment I will merely limit myself to saying the machine will happily loop at sea level at 300 kts and ISA, and gain height at the display weight. 350 kts is not required, and indeed may not be desirable if keeping the display tight is a priority.
Therefore
you could enter your loop below 500ft knowing you'll gain height so you're still going to bottom out above it! But surely that's not the point. You could potentially fly from the apex of the loop through to S&L on the light buffet to fly minimum radius, but again not the point. A minimum entry speed/height at entry and more importantly at the apex are essential. (Also max speed for apex gate).
You say you were a Hunter pilot; AH was a pilot flying the Hunter - not quite the same!