If you spent the bucks on a built motor, You may as well, get it tuned somewhere. after you get a good tune. Leave it alone, work on being consistent. Once you get where it pretty much pulls the same mph time after time, then try to change things. I see far to many people out with new motors, trying to change everything at once, instead of learning the car, and geting a baseline.. I would expect an average 342 to be trapping 117-118. Hell my 306 goes 114, but thats with a great tune, and lots of testing
C