Aaron, I say GO FOR IT!
hehe 300CE is one of my all time favorite benzes, in fact I have one.
I can just imagine seeing that thing when its done. DROOL CITY!
It sounds like a great deal. a new motor shouldn't be too hard to find. maybe you could squeeze in a 500E engine, I think I saw one recently for like $6 or $7k in the local classifieds.
Alon