Will a 350 motor bolt up to 1963 gm tran that had 305 in it?

No, a 350 Chevy small-block engine will likely not bolt directly to a 1963 GM transmission that originally had a 305 in it. While both are small-block Chevrolets, there were significant changes in the bellhousing bolt pattern over the years. A 1963 transmission will have a different bellhousing pattern than one designed for a later 350. You'll need an adapter plate or a transmission with the correct bellhousing.