Honestly, if you have a problem with your foot not being able to lift off the gas, or you drive the car pretty heavy-footed, I would set the boost VERY low, conservative timing, etc. Forget taking it to the track or looking to improve it's performance. It's just going to be a driver until you can build it up right. Others on this thread are right, the ATK motors are generally a mix of parts, and ok with some luck for a daily driver/grocery getter.
Unless you are one really lucky person or like to live dangerously, I would STRONGLY recommend you at least pull the rods/mains and check clearances with a mic, as well as pull the timing cover to make sure the cover isn't scored, and that the timing gears are on good and tight. Since our motors tend to have pretty scary low oil pressure even when working well, it won't hurt to check rod side clearance, as well as the oil pump gears.
Yes, it's a PITA. The extra 5,10,15 hours of your life you spend doing the above will seem as nothing if you compare it to the heartache of finding out the timing gear bolts, or one of the mains, etc.. were not torqued to spec after you have the motor in the car, get it running, and (God forbid, I speak from experience..) have to ask the wife to help you push it back into the garage...
On to happier subjects... At least you have your health!
Billy