Aaron
I would have to wonder what else has been done to this engine in the resent past 
If the engine spins faster after th engine has been run for a short time land sounds like it has less compression then it mostly likley does. how about compression test cold and warm. I would suggest a vacuum gauge on the manifold checked hot and cold.  Read my article on hydraulic lifters and then adjust the valves to 006ths lash. http://www.bostonengine.com/articles/hydraulicll.htm
good luck
Bob Donalds 

Aaron Robinson wrote 
I do have the hot-start problem now though....
What happens is I drive around and park. Van starts/runs fine to there.
Then I come out a while later (15 minutes to a couple of hours) and the
van turns over very quickly (faster seeming than normal), but doesn't
even try to catch. The exhaust smells like gas and I leave it for 15-45
minutes and come back and it will usually start, but with a bit of
difficulty...I have to use the gas pedal.