Phillip, Larry Renger who used to work for Cox, explains this in his thread here:
http://stunthanger.com/smf/index.php?topic=15014.msg137379#msg137379

Robert

Thanks Robert, it sounds to me like it wont make any difference. That will help a lot.

I don't think it makes a difference whether the cylinder points left or right (and down only matters for flooding when you start, really).

Putting the tank on the opposite side of the plane will have a big impact on the mixture as you fly, particularly if the engine doesn't have much suction.  The centripetal effect will tend to force-feed fuel to the engine if you have tank on the inside and carburetor on the outside, or starve it if you go visa-versa.

What about burying the tank in the wing a bit?

What matters a lot on 1/2a or .061 engines is the length of the fuel feed line! A half or 3/4 inch can make a big difference in the way it draws fuel!! Inboard tanks will work fine if the feed line length is kept at a minimum.