welcome aboard!!!
yeah there are ALOT of us up here in this arae... im in garland... people in mesquite, wylie, denton. allen.... all over....
as for a 5.3 its basically the ls1's little brother...
you can find motor and trans combos all over... keep your eyes peeled and you might find one sweet deal
as for a roll pan... your options are endless with places to go..... i know a guy who builds them in his back yard that does BAD ASS work
posi.... i am not sure what type of rear diff you have, but i would suggest check aroudn and ask ALOT of questions.....
i know a place that will do a gear swap installed for under $200.... if you provide the main parts that is