So I've pulled the nailhead and I think I want to swap in a BB 455/TH400 into my '64 Wildcat. who's done it? what do I need to know about fitment issues? are there engine mount adapters or should I just fab my own frame mounts? can I use a TH400 that comes behind a 455? what are the issues with the different trans? things that come to mind are shift linkage, crossmember and bellhousing...are any of these issues?