I guess my first question would be, what tranny are you planning on using? Do not quote me ,but I think you need to graft the rear of a 351 pan to the front of a 302 pan for a 351 swap.?
The rear seal area of the 351w is larger than the 302.
if you use a 302 oil pan and weld the 351w rear pan section to it, make sure the pan clears in a couple areas.
the steering rack, the crossframe, and the starter area.
you best bet would be to use the oil pan for a 302 that was in a mustang ii.
Also make sure that your oil pump pickup is a front sump type, some windsors had rear sump.
You would also want to check clearances of your crank and rods, just to be safe.
When I did the swap years ago, I threw away the old oil pan, (dumb) and used the 351w pan. I ended up cutting and reshaping it to fit, and it still rode on top of the steering rack a little bit.