Replacing/raising the deck without full refinish

[Basketcase]

Hey all. In the next year or so I plan to replace/raise the deck on my 20 Sceptre. If I don't want to go to the trouble of refinishing the whole top half of the boat, what is the alternative? I'd be very doubtful that the gelcoat could be blended at the seam. What do people do?

My deck is solid actually. No soft spots but I suspect wet foam, at least on the starboard side. It lists a tad at the slip. maybe an inch. Only other thing I can think is that the battery is farther outboard on that side than the battery on the other side by about a foot or so. Could that make a significant difference?

I would be shocked if there wasn't some wet foam. Boat is a 78 and all original.