avoid any GM crate engines, they are made with Mexican cast blocks and a pretty piss poor engines, , long as yours isn't already bored .060 over you have a good base to start from, Cyls look good, you got flat tops, clean the carbon off the tops and see if there is any part numbers stamped in to the top to see if its been bored.
find some vortec heads and a good dual plane intake and it will make good power, get rid of that lumpy cam, or you might find it has a round lobe, and get a cam with better low end, .. when it comes to cams bigger isn't always better.
and for the record, the 350 TBI engines make good low end torque,( Which is what you want in a truck motor, not HP) iI picked one up to go in a 80 something GMC shortbed I had , slapped a carb intake on it and it ran great.