My two cents worth is to make sure you use something to "locate" the starter correctly. Early cruise-o-matics used a rubber-covered metal gasket under the starter mounting flange to correctly center the starter in the correct position. Please don't make the mistake of thinking the starter bolts do a "good enough" job of putting the starter in the correct position. Don't quote me on this but I think Ford switched from that rubber-covered metal gasket around 1962 and began using a block plate gasket between the engine and bellhousing. This full size metal gasket correctly centers the starter in the right spot so it will engage the flywheel teeth correctly without either gear getting chewed up. The block plate gaskets are available if you didn't get it when you acquired the '64 transmission. Also, if the transmission is out then you have the option of changing the flywheel to the higher teeth count so you can use a modern starter rather than the older version. But that's entirely up to you. I just wanted to mention it while it's conveniently apart. As far as other specifics, I would imagine that transmission cooler lines may be routed differently but I'm not aware of any major differences that would prevent the swap.