You're on the right track, but have a long way to go.
There are many issues that will need to be addressed and resolved to achieve your desired objectives.
Getting the right and a good engine from a truly reputable and expereinced dealer is very important. Just as important, if not more important, is the installation itself including an assessment of existing associated components and infrastructure such as engine mounting configuration, engine controls, cabling & instrument displays, electrical cabling, water pick-up and discharge, cooling configuration, exhaust discharge, prop shaft & coupling & stuffing box, prop, alignment, etc.
The installation should be done by a qualified, certified & experienced professional.