swinger 360

http://www.engine-swaps.com/ Has the swap kit needed for the V-8 swap. Any header manufacturer will have headers for this car/engine combo. The k frame being a /6 is not a problem.
Do a search on headers and see. (Go to the exhaust section.)
A top end rebuild can cause problems on the lower end if it is weak.
The steering box is of no concern.

Now, a strong combo.....you'll get lots of opinions here on that. Sooo, how much power do you want to create?
On the cheap type build;
Swap meet for a used carb, Torker II or Performer and headers. I would spend the money on a new cam. You didn't say what gears your going to use, soooo a cam would be near impossible to recomend.

Brand spanking new parts would be; A RPM intake and heads, headers and carb to match.
A 360 is good to make use of a 600 for melo/mileage street manors, 650 for a bit of a hop up, 750 for some serious power making.