HW50 Mk1 tampering. Fettlers look away now!

[deejayuu]

Thanks for looking. Fancied a tamper with the 50 piston. It didn't go well.
First thought, machine the head for O ring or AA type seal. Too hard for limited tool/skill set.
Next, remove head and latch rod. Not easy. The thin tube is clenched into a groove around the head,
Fortunately the tube is soft enough to cut with hacksaw. Spigot on latch rod snapped and too hard as per head.
Plan is, make a mild steel/alloy/Delrin head. Anneal/rework/thread the rod end.
Objective is increased stroke. All physically possible medically approved suggestions welcome