ya it would be better to have the duels u will wish u did it after u put it together if u dont.
with the auto tranny it might be allright but ur best bet would be too put in the duels or atleast some 4.7 gear sets.
a friend of myne is building a toy with 38's and a built 350 turbo 350 with duel transfer case's and 4.10 high pinions.
ill let ya know how well it does after its done.