I will give you $500 sight un-seen...
Seriously you have one of the most desirable ski boats and engine combos out there. You have the best looks, hull and EFI.
I agree it does not sound like a rebuild. There is some good advice here on the electrical and fuel delivery side.
The other issue that the early LT1s suffered from was the cooling system was not routed properly and air bubbles developed in the upper part of the engine. On a hot day, this could be giving you temperature spikes, especially after you sit for a few and get heat soak. There is a very simple fix for this and it is pretty easy to tell if you LT1 has the fix. It basically deals with a pass over tube being on the front or rear of the heads. There are a couple of threads here that talk about it, one that even has a part number and a dealer in some place like MN that ships the parts total for around $25.