I wouldn't reduce the length of the skirt just to even it up. Reducing the skirt on one side is bad practice in my eyes but I see why they had to do it.

The part of the skirt you are reducing is also the most important part being where the piston is at its largest. I have personally had one skirt fail on a 300 kit and I know of another where two failed.

If you want to stick with a 300 I would modify the crank cases to allow for a full proper skirt.
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If I have to take the carbs off once more...