Welcome to the wire!

Personally I think that replacing the heads will be a lot of unnecessary cost and work, in your case. It sounds like you're pretty mechanically inclined and should be able to tackle the valve stem seals without removing the heads (with the compression readings you've got I don't see any reason to pull them). It's just a matter of pulling the cams and rockers off to get to the seals - it is VERY tight around the valve springs but with patience it can be done.

You're located right in between the Montero owners in Phoenix and the East Valley guys - there are a lot of great people here that are more than willing to help with tools or assistance if needed, so don't be afraid to ask. Our local forum is here - http://www.4x4wire.com/forums/postlist.php?Cat=0&Board=azcrawlercrew&page=0