Briggs power head swap

Well I'm new around here, I have lurked for a while though.
It turned out the 3 hp Jonson I bought as a "runner" had badly scored pistons and I could not get it running properly. I was given a 3.5 Briggs from a pressure washer that I figured would be a candidate for a new powerhead.
My first step was building a mounting plate that bolted to the leg.
Second step was figuring out how to improvise a keyway to lock the 7/16 lovejoy coupler onto the original shaft. I ended up drilling and tapping it to 1/4 NF and making a "set screw/keyway"


This is the complete adapter plate.


Here is the complete project. The adapter plate was pretty heavy so I cut some speed holes in it.


My to do list consists of
Throttle control
Steering arm
Replace gas cap with non vented cap and vent tank into air filter housing

I also picked up a 1974 9.5 eske that had a bad power head. I had a like new 6.5 Briggs that I wanted to use on the eske.
It also received a 7/16 lovejoy that I drilled and tapped and installed a set screw into.
Here is the mounting plate I made for it.


It's all done, aside from re installing the fuel tank and extending the exhaust.


I had to swap a cast iron flywheel from a 5 hp onto the 6.5. The aluminum flywheel was not letting it idle low. I had to file a new keyway into the 5 hp flywheel to index it properly because the ignition was not timed properly.