That is still a very nice truck, and nice work so far! As far as the exhaust goes, if you want loud you could start with some nice headers and go from there. Usually to have an exhaust shop run the pipes for you it doesn't cost much. I didn't see if you have converted to HEI yet, that will boost performance as well. Also, if you're interested in doing the engine yourself check out northern auto parts. (
www.northernautoparts.com) They have a very affordable 350 master kit, along with 383 kits. You should be able to have the block machined and build a nice healthy powerplant yourself for less than $1000. I've ordered many parts from them, 3 master engine kits and a couple performance cam kits. Very nice company to deal with.
Good Luck!