Motorhead Ted I have been running a fluid for 15 years and no problems. There are a couple of things with your setup, The WHOLE rotating assembly should have been done as a whole. This is dampener,spacer, pulley, crank, assembly weight of rods, pistons,pins,
oil, and bearings, and flywheel. All should have been indexed. This will give you the best setup and least vibrations and harmonics from the motor.
The only down side I have found with ATI is the bolt holes for the pulley are for BBC and not FE. There is a little note in the instructions to tell you that, AFTER you own the dampener. Other side note, with a fluid dampener and running and aluminum block motor, allow both to warm up before driving. Coolant temp will raise quick to 180+f but
oil temp takes about 2-3 minutes. I have 2 shelby blocks and have been very happy with them.
I run a windage tray in my motor,(482). I don't think it is needed if you are going to just street drive the car. It's alot more important to have good
oil pressure and run 7-9 quarts of oil in the motor. I have heard that windage trays can give you a 2-15 hp pickup. This is on motors with no lower side skirts. Hemi and FE both have long skirts. For the most part the oil ends up back in the pan without alot or airation to it. Other thing is install a preoiler for the motor. Accusump sells a nice 2-3 quart setup. This will give you a 30-40 psi buildup before starting the motor. Will also save motor on high sweeping "G" turns. Just a thought. Good luck with build Rick L. Ps flywheel was balanced and indexed to crankshaft?