IIRC, TTI has thru-the-chassis available for early As. I ran fenderwell headers on my '65 Valiant w/ a 340- I believe they are still available if you don't mind cutting out the inner fender a little. One motor mount is different- you can either modify a mount or buy new from someplace like Schumacher. If you were in the 12s w/ your Dakota, it shouldn't take much to see 11s.
From the Moparts archive-

http://www.moparts.org/Tech/Archive/smallblock/11.html

Some good info available here-

http://www.earlycuda.org/tech.htm




Tim