Rebuild isn't starting

[CowgirlKatie]

So we took a freshly rebuilt engine out of a 1969 grain truck and the manifold had a crack in it and eventually blow out and fried the electrical and the truck sat in a field for 5 years. It's going into my '72 step side long box so we took the engine all the way apart to check everything, and sure enough there's no ridge in the cylinders, no crud in the oil pan, no build up in the intake or heads, and the cam looked fairly new with no wear marks visible. So we put all seals in it and torqued everything to spec, painted it, changed it from points to HEI, and stuck in my pickup with a new Edelbrock 650. Got everything hooked up properly and it won't fire up. The starter works, the fuel pump works, it has spark, the timing is spot on, but it's almost acting like it doesn't have compression. I don't know if the valves aren't set properly? There aren't any vacuum leaks that I could find