Here's an idea for you, automatic trans side mount kit from Danchuks. Will not be a bolt in, but an idea in any case, similar problem solved re. 55 56 & 57 Chevys with less than optimal factory side trany mounts.
http://www.danchuk.com/ItemForm.aspx?Item=870


It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed