if you search a bit, Vile Zambonie just did this to his '74 GMC C1500. he posted good pics and even a video of the truck afterwards...
as far as positives/negatives? well, positives is that it looks cool to see a 1-ton 4x4 shortbed (i'm gonna have one soon), as a negative, you lose bedspace, the ride will be a little worse due to the shorter wheelbase...you can't really haul a gooseneck trailer anymore (if you did to begin with)...otherwise...it's not really that bad...if you want it, GO FOR IT!
BTW, welcome aboard!