64 pushbutton tranny to 66 slant six

Yes the 64 trans will bolt to the 66 engine. not sure of what upgrades can be done to the transmission. You may want to consider putting a 68-76 225 crank in it and using the later 904 trans because you can get off the shelf torque converters for it and not have to pay for custom built ones. Hey also there is a realy good book out there on chrysler engine interchanges title is How to Build High Performance Chrysler Engines by Frank Adkins ISBN:1-884089-54-2 should be about 20 usd

Brian