oh yeah .... my 5 liter should be like driveing a hot rod

158hp @ 3800 and 262ft/lbs @ 3800 vs 225 -240hp and well over 300 ft/lbs

 

Almost done with a 351m rebuild - curious about what kind of hp increase I might hope to experience - the rebuild has a comp cam, performer intake, and holley 650. Any ideas?

 

To make that change is gonna cost a lot more than you listed in parts and effort and time. Almost nothing swaps over.

 

New pistons or heads? Any increase in compression?
Which Comp Cam (that's a huge part of this!)?
Which Holley 650?
Which timing chain set, and if applicable, what advance/retard did you use?

While maybe not a massive increase, most reports are pretty good regarding how much better the engine feels vs before the rebuild and re-camming.
Whether you get an accurate answer or not, good luck and have fun with it! Hope it's a big improvement.

Oh, and I have to ask... Do you know the proper procedure for the initial cam break-in over the first 20 to 30 minutes of the engine's life?
Sorry if you already know all that's needed, but many still don't so I wanted to make sure before anything bad happens.

Paul