Compression on a 2-stroke usually comes in about 120. I've see running engines with only 100psi but generally, the more the better. They're all different, the important thing is that they should be close to the same. A very typical test may read 120 on one cyl. and 125 on the other. General rule of thumb is that the difference of the cylinders should not exceed 10% of the average however they are usually 5psi apart. These two engines are of the same family. Most parts should interchange. Usually the extra HP is in the top end, one may turn another 500RPM or something. The 33 may have a few differences like a higher compression piston and a different exhaust plate but, such drastic changes are mostly found on the larger engines of the same family like a 90 and 115. In your case its likely just carb jetting and timing, etc. The reason for two models to be so similar but different may simply be for HP ratings on boats. If you're looking to make one good motor out of two bad ones you shouldn't have any trouble.
