Personally, I think a M1008 is a bad idea for a trail rig, compared to a M1009. This is only based on my experience in Wa though, so your trials may be more full size ready.
If I was doing it, I would prolly do a shackle flip in the rear, and a AAL or new leaf pack up front, netting you a total of about 4 inches. I would then add something to your passenger side mirror so you can see your rear tire and avoid curbs. Shocks are then up to you, and I cant think of what else has to be done for a 3-4 inch lift.
Now, I drive like an old man on the streets, and almost never down the freeway, so I LOVE low gears. My 1975 C20 has a 350, non over drive trans, and 4.56, I love it! That is on 30 inch tires.
Things like re-gears are kinda expensive, and I wouldnt want to try one myself. So, I would be looking for a cheap M1008 that you can rip the axles out of, and then modify the rear to fit your truck. Shouldnt cost much to have done by the pros, or you can do it yourself. The other option is a rear 12 or 14 bolt that bolts right in. (Maybe a 1 ton suburban?) and pay to have 4.56s installed, then track down the front, which will be much easier to find.
So now we have 3-4 inches in the front, and 4 in the back, and 4.11-4.56 gears on 12 or 14 bolt axles. Hell ya your ready for some tires! If you plan on really off-roading hard, you want under a 35, but I think K-5s almost always look too big for the tires, unless the top is off. Idk why, but K5s can make ever 38s look small!
I would go with the 37 inch tires at this point. Yup, your going to have to some minor trimming, but they will look great! This will also give you a gear ratio that will be pretty good for Daily driving. Keep in mind, this is now a BIG truck, you will have difficulty parking!
The build I described though is in-expensive, and you should get decent fuel millage. I wouldnt re-gear a 10 bolt.... Not unless its in a sports car. Big tires+10 bolt=bad day
Idk, that is what I might do. I found that there were not enough places to take my civy K5 out to get it dirty, so I traded it for a jeep. Now, I am getting a M1008, and I plan on adding bigger tires, but it will be my DD, and the one that comes to rescue the jeep when I get stuck or broken.
I figure if the M1008 has a top speed of 55, with stock sized tires, then your new top speed would be right around 65.... If my information is correct. It might not be! I would also be far more ready to put a 700R4 in than try to re-gear it myself.... Which is my plan with the M1008 when I get it.