Convert 1.665AR to 1.33AR

[zabolots]

I've got a video pulled from an Australian source that has the following format (MediaInfo output):

Video #0
Codec                : On2 VP6
PlayTime             : 8mn 34s
Bit rate             : 400 Kbps
Width                : 428 pixels
Height               : 257 pixels
Display Aspect ratio : 1.665
Frame rate           : 12.000 fps
Bits/(Pixel*Frame)   : 0.303

I'm trying to convert it to a 4:3 video without the AR being all screwed up. Any ideas on how to do this? How much should I crop and/or pad to get the video to have a 4:3 AR without losing a lot of the picture?

[Midzuki]

Add 10 pixels of black border to the left, 10 pixels to the right,
39 pixels to the top, and 40 pixels to the bottom
(result = 448x336, AR = 4:3).

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