suspension set up.

[Falcon 269]

I'm 16 stone and 6'4" if this helps.

It does, but not your suspension.

The rear shock on the Gen 1 is woefully undersprung and riders above 14st in kit will need max preload to achieve the 30 - 35% sag target.  The shock oil and gas also get tired after 10k miles and above.  Both factors would explain the bottoming out you're getting.

For now, set max preload on the shock and compression damping to maybe 1 - 2 clicks out from max.  Set rebound damping to 4 clicks out then send Devilsyam a PM to ask about R6 shock availability.

Up front, I'd offer 2 rings preload showing with compression damping at 10 clicks out from max and rebound at 3 clicks out.  Try those initially and adjust to taste.