Evan,
I am in the same boat. Getting ready to install a 2.1L engine with 1.9L
heads. I was not expecting any problems of which you speak. I guess you
could retard the timing if detonation is a problem.  On a side note; In the
good ole days, when you ordered a clutch "KIT" , didn't it always come with
a throwout bearing?
It's always something....

Ken Lewis
http://neksiwel.20m.com/
Vanagon mods, tech info and O2 sensor help