Ok, did some testing on the F4U-1A.
For the test, I used the FW-190D, with a wingspan of 34ft, so probably about as close on this test I'll get. Also it's one of the offline drones, so I'd rather use that than try and do this in a furball.

Anyway, first I tried to keep the Dora in the sights. The screen was taken from the default head position. Zoom was used to make it easier to line up on the target.

Here, the range counter indicates the 190 is 200yds out. According to Mace, at 200yds distance the 190's wingtips should be roughly touching the edge of the inner ring. However here, the wings are touching the OUTER circle, Roughly double the size it SHOULD be.

In this image, the counter shows the Dora at 400yds. The wingtips are touching the inner circle, and once again according to Mace's data this is approximately TWICE the distance it should be.
Realizing the range counter doesn't give the exact range, I next used the target to try and get a more accurate picture.

In this image, I set the target to a distance of 10yds, about as close as I could usefully make it, then took a screen from the exterior to get a comparison. I'm slightly zoomed in on the aircraft here to get ground clutter out of the way (figured I'd do this on the ground to make it easier to line up on the center of the target).
Roughly, the Dora's wingspan is equivalent to the diameter of the second ring.

As best I could, I then lined the F4U's sight on the target set at 200yds distance. Even though I don't have a PERFECT measure of the Dora's wingspan in relation to the target, this image still falls almost EXACTLY on the test using the range counter and Dora illustrated above.
The gun sight in the F4U-1A, 1C, 1D and 4 (since they all use the same reflector setup) appears just around HALF the size it should be (accounting for any distortion due to the target being set 10yds ahead of the Dora, and that the Dora has an additional 2ft on either wingtip).

Here is the F4U-1A's sight roughly adjusted, based on the data from this test.