[olddog]

I'm voting with Barry , as the cam being off would explain the low compression and low vacuum.

If you have the tools and know how, you can find where the valves are opening and closing. This will tell you if the timing chain is off a tooth, without pulling it apart. All you need is a degree wheel and dial indicator on a valve.

Quick and dirty check is see where #1 exhaust valve closes then back up until the intake valve closes. TDC should be about half way between these two points.

If the timing at the cam is not off, check how close you are to bottoming out the lifters. If the heads were milled quite a bit and block deck squared up, that sure could bite you.