I am running a PDI front mount intercooler on my narrow front 79, 1hd-fte. Works incredibly well. Top mount wise, a stock intercooler with fans will cool a modified 1vd ftv well enough, normally get swapped out on the v8s once power is above the 200rwkw and 900rwnm mark. Otherwise, cross country make a good top mount, but both are located down under if that puts you off. Whatever you do, you will need to custom mount the intercooler to work with the 1hdft and factory good scoop.
Before you order anything, check what clearance you have between the top of the engine and the underside of the hood. My bet is that there won't be enough room for a good size cooler and fans. If making big power, I would get the PDI wide front replacement front mount intercooler. Another thing to consider is that the top mount will make working in the engine bay a pia.