Let me start off by saying that Angelina has replacement tanks. They are two custom built exact aluminum replicas of the original leaking sheet metal tanks. At the time, the engine and transmission came out, the entire engine room was "bilge coated", new shaft, log and packing were installed. My engine room is a work of art. About 8 large in 1994.
Would I do this again?
I would remove the leaking tanks and replace with several large plastic storage tanks and a day tank.
If the existing tanks were not leaking (and didn't appear likely) I would coat them inside and out with some of these magic coatings recommended here. And if in a few years they started leaking? See the previous paragraph.
You do need to immediately address all deck leaks and keep the engine room and tanks dry.
34' Marine Trader