put a 351M in it and build it up a bit... here, i got a video for ya, its of my pickup, i have a 351M in it..(i tryed to embed them but it wouldn't work)
http://www.supermotors.net/getfile/6...friday-030.avi
http://www.supermotors.net/getfile/6...monday-020.avi

 

351M has the right setup ideas. the 390 motor mounts work wtih 400 towers if you flip them sides driver-0passenger and vise/versa the cut off the bolt hole corner that doesn't line up but the are better more secure ways of fitting a BB in the 6's old home.

 

How many of these "70's" trucks with 460's had 4WD?

None.

No 460 4WD's until 1983.

 

if it were me id go with a 351w with an aftermarket 4bl intake and a good carb and dual ex.