Bakeoff

So, my dad calls me a few weeks ago and said his 96 Windstar is running like hell. I told him to swing by my house and I'd take a look. In a half hour I found enough evidence that pointed at the head gasket, that I didn't bother doing a compression test. (one spark plug had baked on green crap, it only idled rough at warm start up, etc)

So, being a good son I told him I'd get all the parts at wholesale and fix it.
Now I'm no pushrod fan since I've been working on 500whp Hondas using sohc and dohc engines, so I had to call my buddy Jeff. He worked in Cali building motors professionally for a few years before moving back to Minnesota. So, with the 30+ engine swaps I've done and his experience, I figured we would be fine.

We got it all back together last night, started it, saw that it ran, and I went to bed. I finished putting the wiper cowel and whatnot on today and started it up for the test drive. Upon driving it, it felt like it was missing. Then listening to it at idle it even seemed a bit off (didn't notice from the cabin when I started it the night before).

Check:
firing order
vaccum
no check engine light
all plugs and wires were replaced
spark on all cylinders
good compression numbers

Yet it idles poorly and is worse under load. It sounds like it's missing. We never touched the timing. Any help would be awesome, cause I'd love to have the van out of my garage and back in my dad's hands.