[Runequest] Contemplating House Rule -- Advice?

[lev at rpgreview.net]

> Also going back to our magic number, receiving a single blow to the head,
> chest or abdomen that is double the hitpoints +6 is instant death.

I must say I really dislike the "magic number". It might make sense on a
human scale but it breaks down when it's applied to everything from a
rubble runner to a giant. For that reason I prefer the RQ3 (and later?
can't remember) method of negative locational hit points...