[Water Rat]

I have a '78 23' Sceptre. When I repowered with a 7.4 Bravo 1, the shop doing the installation had the same issue. They did what has been suggested here, cut-down the center stringer by way of the oil pan and now, 1700 hours later, no issues.

One thing I would strongly recommend is heavily coating the oil pan with some type of epoxy or other coating to prevent corrosion, especially if it is a stamped steel pan. Because it sits so low in the hull, it will be constantly splashed with whatever water finds it's way into the bilge - then thanks to engine heat, creates it's own saltwater bath. I tend to go through oil pans at the rate of one every 3-4 years.

Last, please post pictures - would love to see your installation.
Good luck.