Bill,
My advice before you go down the head swirling of prop opinions & options is to let us know what motor hole you are mounted in.
5400 rpms is far short of what that should be.
Thanks for the comments. It appears to me that it is mounted on the third hole from the top. To clarify, this positions motor higher up on the boat. Mounting through the top hole would position motor lower on boat and water. It looks like there may be 4 possible mounting hole options, although I may be missing one that is covered up. Thanks. Bill