It will all bolt in, driveshaft may need to be changed depending on if you current one is the long or short tail TH350. I am doing a 97 vortec 350 swap using the complete wiring from a tahoe (not done im doing wiring on it now). an aftermarket harness is the easy route but I looked up the harness for mine and it is over $700 so Ill just do it the hard way. ECM program depends on what you modify if you keep the O2 sensors, EGR, Catalytic converters etc you should be able to use the stock ECM, some have a VATS vehicle anti theft system that may need to be eliminated by reprogramming. that and I beleive you will need different gauges for the electronic speedo VSS.
Heres one but its a 92 roadmaster drivetrain into a squarebody. lots of good wiring info in this thread!
http://67-72chevytrucks.com/vboard/s...d.php?t=356697