Is it worth the $ to build a 5.9 Magnum (or LA 360) without making it a stroker?

A good valve job and mild porting on the stock heads will show very good gains for little investment. Also like has been said, the camshaft is a big limiting factor. All 5.2/5.9 cams were designed for trucks and heavy suvs. I have had oregon cams regrind a few for me and love them. Remember an engine is just an air pump, the better it can breathe the better it will run.