Depends how worn it is and how hot it runs.
10W-30 should be fine but if you see the oil runs hot, or that the engine seems to be eating oil, then try 10W-40. My last 360 was pretty worn and was getting the previous generation of Rotella 5W-40 synthetic T6. The lower W grade is a little easier on the engine when cold. If you aren't in a cold climate or not doing a lot of short runs, then its not so important.
if you want to get into the ZDDP game, look for an oil with at least 600 and no more than 1400 ppm. Valve spring pressures on a stock 360 cam are not anywhere in the range where one should be sweating this.
'85 Grand Wagoneer
360 727auto, NP229
body by beer (PO)
carries wood inside
no "wood" outside
My other car is a fish