A local gentleman in a neighboring town is building a Wittman Tailwind W-10. He bought a fiberglass cowl and was unhappy with it so he told me if I can make it work for my W8, then I can have it.
Perhaps this will be the world's first attempt to fit a W-10 cowl onto a W8!
To phrase this simply, this is going to be a challenge!
The upper and lower pieces are not "matched" for lack of a better term. If the two pieces were mated together as is, the upper and lower areas near the spinner would not be flat or flush and the lower half would mount "crooked" as I was required to cut off more material from the pilot side than the passenger side.
The red arrows in this picture show that getting these two parts to fit together is going to be a bit of a challenge. The yellow-dashed line is roughly how much of a tapered-cut was eventually required to remove material. I ended up removing approximately 1/4" of material from the front which then tapered to about 7/8" on the pilot side. The passenger side tapered to about 1/2".
The tape measure has no relevance to this task (I was measuring for a spinner), but the arrows indicate how much material needed to be trimmed away.
The passenger side didn't require quite as much work.
This is how they fit together after all the cutting, trimming, filing, and shaping was done. Unfortunately, there was quite a bit of inconsistency in the material thickness throughout the entire structure. Some areas were about 1/8" thick. Other areas especially around the curves bulged to 1/4" thick (yellow arrow). There's no way that I was going to make the upper and lower halves mount flush there.
The black sharpie line should give an indication of the tapering cuts I was making on the lower half in order to get the front/spinner area to have a "flat" surface.