truck is looking good. all your hard work is about to pay off. i would be very concerned about that fan. did you make the adapter all perfectly true? original pulleys have a raised up shoulder to get the fan hub dead center, and keep it there. have you spun it around to watch how straight it runs? i would be more concerned about that then how much it weighs. these things will fly right thru the hood, or take your face off if you are standing there. an original fan should not be too hard to find, or too expensive.