Actually it's the more costly fix. Plug the coolant ports and reuse your original UIM. The permanent and cheaper fix.
Racer: you can't really expect that 16 year old gaskets... no matter the mileage should be magically perfect. It's like saying you never expect a tire to dry rot. Yet there's rules out there stating no tire over 10 years will be mounted on a rim by a shop. Because.. after that time, the tire quality is compromised.
Yes that's true. I just wish the previous owners would have taken care of it. Then I wouldn't be stuck with spending all my money on it.