Overdrive in Early A

I‘ve spent hours looking through the old posts on this subject, but I have found very little real first hand information on installing an OD trans in an early A. I am not interested in a Gear Vendors unit, or on information about 67 and up OD installs. Is there someone in FABO land that has installed a 42RH or a 200-4r in a 63-66 A body?
There's some on here somewhere. You just have to search. Contrary to what the admins and mods say, I think the search function leaves a lot to be desired. But it's been done. Just know, you have a good bit of transmission tunnel modification ahead of you, as well as making up a custom cross member and of course drive shaft and "whatever" you will do for adapter plate and flex plate.