Depends on whether you are placing it in the factory coffin, or below an aftermarket sole.
Factory coffin, I don't think so. I think you're looking at more like 6" height plus fill, etc.
Below deck, possibly, but your stringers are tapered so that will play into it too.
In my 1986 170, I put the Moeller 35 gallon 69.5"x16"x8" tank below my new deck, and it was a tight squeeze vertically and was pretty close laterally.
This is how the 16" wide x 8" high tank sits below deck, dry fit photo. Fill etc. will take another few inches of height depending on tank.
