If a drill wont spin the motor over with the plugs out
its bound up some where. While your convinced it is the
cylinders, and you may be correct, it could also be in
the drive shaft or the lower unit. It may be difficult to
determine with the cylinders off, but while they are,
rotate the motor to see if you can tell if it is in fact
the cylinders that is the issue.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.