Good for you--I think you'll enjoy it.
One question--how many miles?
I know you are trying to keep the mods down and adding a third radiator is a good way to go, but have you thought about doing the IMSB change out and/or various things you can do to prevent that from becoming a problem?
Here's one place to start to gather info but certainly not the only one:
Products: Performance and Enhancement Products for your Porsche