Gruesome Chops for OD&D Fighting-Men

I haven't had a regular game in a few months, but that hasn't stopped me from tinkering with my house rules. This is an attempt to give 0e fighting-men a bit more oomph. What do you think?

Gruesome Chops

A roll of 20 to-hit or a roll of maximum damage gives the Fighting-Man the opportunity to make a Gruesome Chop. The player chooses the hit location; here are some examples:

1. Eyeball run through. Monsters with hit dice fewer than or equal to the fighting-man must Save or be kebab'd. Monsters with more hit dice lose an eye* (-2 to hit, cyclops -4).
2. Neck slit. Monsters with hit dice fewer than or equal to the fighting-man must Save or suffer beheading. Monsters with more hit dice loose their voices, and must Save when using a breath weapon.
3. Limb chop. Monsters with hit dice fewer than or equal to the fighting-man must Save or be dismembered and bleed out. Monsters with more hit dice (and four or fewer legs) are reduced to zero movement.
4. Bifurcation (horizontal or vertical). Monsters with hit dice fewer than or equal to the fighting-man must Save or be bisected.
5. Evisceration. Monsters with hit dice fewer than or equal to the fighting-man must Save or spill their guts.
6. Ribcage crush. Monsters with hit dice fewer than or equal to the fighting-man must Save or suffocate.
7. Sever artery. Monsters with hit dice fewer than or equal to the fighting-man must Save or BLOOD SPRINKLER!
8. Break the monster's sword, splinter its shield, sunder its sandals, etc.
9. Force the monster to fall back ten or twenty feet to the spot you want them (over pit trap, under portcullis, etc.).
10. Impale. Monsters with hit dice fewer than or equal to the fighting-man must Save or wriggle in grotesque death throes. Monsters with more hit dice are pinned (movement zero).

Any monster that survives a Gruesome Chop immediately checks morale.

N.B. — Most monsters do not make Gruesome Chops, but enemy Fighting-Men do.