What is the correct way to put the faceplate back on to my newly rebuilt 401? Also should I turn the crank so piston 1 is up for setting the timing before I put the motor back in or does it matter,thank you.
There are seven (7) holes in the centre section of the flexplate - 6 bolt holes and the final hole that lines up with a matching hole in the crank. If you don't line this up you'll get severe vibrations. Doesn't matter at all where the timing marks are when you put the engine in; I usually cram them in and sort the timing out after its all buttoned up.
Even if you set it to number 1, you are going to turn the engine to hook up the Torque Converter to the flex plate. I would set number 1 after hooking that up and before putting the passenger side exhaust manifold on. It makes it easier to stick your finger in and tell when the valves close.
Just remember that the piston is at TDC twice, once on the compression stroke and once on the exhaust stroke. The big mistake made is to just line up the balancer mark and timing tab mark and install the distributor. You have a 50% chance (more if you believe in Murphy's Law) of being wrong, 180* out. The distributor has to go in on the compression stroke.
What I did with the flex plate on mine was give it a light cleaning, and then made sure I reinstalled it in the exact same position as it was on the crank. Thus far there have been no issues. The wild card is the torque converter; - it was completely overhauled and as such, and unknown quality. I have no idea whether it's in balance or not; - I can only assume it isn't bad because it hasn't shook itself apart yet.