PP manifold doesn't line up?

I have a Proffessional Products lower manifold on my 351w and when I was installing it, about 3 or 4 bolts didn't line up/tighten. When I go to torque them, they get tight, then just spin. It felt like the some of the bolts aren't long enough, so I went and bought some ss ARP intake bolts, and still the same thing.

Has anybody else experienced this? I went and got some studs, so I guess we'll see what happens? Just want some thoughts before I take it off and put studs in.