best gears??

[RAMBCS]

I have a '98 12v hooked up to a NV4500 5 speed tranny. I currently have 33" tires but plan on going up to atleast 35" and maybe 38". My gears are 3.55. Will the 3.55's handle the larger tires adequately or should I shorten the ratio to 3.73 or 4.10? The engine has been turned up to approx. 330hp and 750tq. I have this combo in a '94 F350 crew cab long bed and get about 16.5 mpg with a mix of city and highway driving. I absolutely love the combo with the size of the ford crew cab and the power/reliabilty of the ctd. I have lots of little things to do to the truck because the truck started its life as a "gasser", but I am looking to beef up the drive line in about a month starting with the gears (if necessary) and a 4-6 inch lift. But the gears are my main question right now. Thanks for any input.

[Dodgezilla]

I used to own a 12 valve with 3:55s and 33" tires and 5 speed. It was slug but it got 22 mpg. Had I kept it, I would have definitely gone to at least 4:10s.. Mine was totally stock though...

[bigdrake]

Tires that big even with I diesel I think I'd go 4.10s.

I've got 285s (approx. 32.5") with mine, and the 4.10s feel just about right...