I think the problem adding an extra dice (which isn't the d6 as used exclusively in the game) slows things a bit by adding an extra roll factor. Plus, having the game be d6 exclusively, and then using a d8 just doesn't work for me aesthetically, but that's cuz I'm odd.
I'd go with either:
1) Reducing starting Health (and limiting the amount gained each level).
2) Have weapons do their maximum damage on a hit (which also has the benefit of speeding things slightly because it takes the roll out of the equation).
Either approach is far quicker and easier to implement and use than most others, and that also feels more in-keeping with the ruleset.
Freelancer: AFMBE, A|State, Atlantis, C&C, Faery's Tale Deluxe, Godlike, Hellas, Hollow Earth Exp., Iron Kingdoms d20, No Quarter, Omni, Talislanta, UnMet, Waste World, Wild Talents, etc.