Bill:
About
oil coolers - they don't care about flow direction
About draining the
oil and checking for bearing material - that is what I would do - or you could start it up and listen very carefully for any kind of knocking.....but I would bet money that it is OK. If you do hear any knocking, running it briefly isn't going to cause much more damage than you already have.
You could also cut the
oil filter apart and look for bearing material after you run it for a bit.
Bill - this is my opinion based on years of building race engines for myself.
If I had an engine building business I would take the pan off and look. I guess all it is going to cost to do that is time and a few pan gaskets.
Good luck.