Chris speaks the truth (as usual)... the additional thing that can be said about the upgrade vs. swap is that the upgraded/rebuilt engine is now 'fresh'.
There are folks (EBS for one) that will bore out your cylinders and replate them. I seem to rcall a $2k ish price for that work and new pistons.
figure a cam regrind $500+... valve work while you're in there $500+... twin plugging $??? et cetera
I suspect that this will be the route that I will go at some point if my 3.2 gets tired. I think the big question will be whether or not to twin plug since its going to be another couple thousand.... and then the PMO's for $3k...
wait a second... thats starting to add up.
-Bernie