Just curious, how did you fit the 14hp into the 107 frame with its larger diameter flywheel? Did you use a flywheel and tin from a 12hp? I don't see any frame mods to fit it like the 147 has. Unless that is not the 107 in the photo that has the 14hp.
I had much that problem some years ago. Found an original 100, short of an engine but with a gearbox and creeper drive, as a garden ornament in a flower bed. It followed me home. Creeper drive seized, made a set of gears fit and then started the hunt for an motor. Found a Lincoln welder with a 12 Hp, built a sump out of flat-bar and a plate. Cut and reinforced the frame. Nice thing about the 12 Hp is the built in stator and separate starter. The starter brackets tend to break but are make-able. the attached picture shows the reinforcing strip on one side, same on other side
It started when a friend gave me a wide pan 14hp Kohler from a Snapper. After researching how the block could be cut and welded, etc. I gave up on that. Didn't want to chop up the frame. Bought a narrow 14hp block and crank on eBay. Built it up using the parts from junk 10hp and 12hp engines, including the shroud, flywheel, head. I believe it is the same engine a 147 would have.
I shaved about 0.050 from the head on the milling machine. Removed the balance gears. Lightened the piston and rod to compensate, The balance factor was measured, and is within acceptable limits.
It finally has a respectable amount of power.