theres alot of options for you, you asked a loaded question though.
do you wheel this rig? or just a daily driver? and cost is always a factor.
a custom shaft may work like knotts recomended, however, our front shafts already have double cardan joint on the t-case side so i dont know how much better it could possibly get unless you got a double CV flangged style shaft.
body lift is a great, cheap, semi-easy option. specially if your happy with how your truck rides and handles now.
if you wheel this truck, one option might be to look for a HP dana 60. this route would be alot more work and money but its a worth while swap IMO
a clocked transfercase is another good option like badblackram06. you may also look into a devorced case. and again if you wheel the truck you could double up your cases and get a super low low gear and amazing driveline angles.
i'd hit up the forum build threads and see what other guys have done, thats why im on here now lol