I did something not quite similar really, just that the way the Honda name was on parts was cut away, I obliterated a UL Symbol.
I drilled through a UL Symbol on a mod I made to a portable tape player/radio/CD player when I wanted to have it run off the 12 volts from my car. I out a BNC connector where the plastic had that symbol.
The way you did the fins looks like all the same cooling will be effective, just the looks of a newer engine changed to one that used external push rod etc. Old time style, Neat!