Ford racing sells an oil pan upgrade for the 15-17 gen 2 engines. It comes with an 18+ poly oil pan, new pick up tube, and a new oil pump with billet gears. The reason for the new pump is the 18+ pick up tube will not bolt to the 15-17 style pump so they give you a 18+ pump also with billet gears thrown in. The kit retails for around 600. Knowing that, you could use a 15-17 pan, pick up tube, and pump and retrofit them to your car. The 15-17's had a steel 8qt pan. To change them you need to lift the engine and lower the K member to gain an additional 4-5" clearance to get the pan out, otherwise you need to pull the engine. Other things you need to do, drain the radiator and pull the water pump, remove the balancer, remove the front cover, and remove the timing chains, then you have to put it all back together. Seems like a lot of work just to get a metal oil pan.
A buddy of mine has a first gen lightning and back in the 90's ford issued a recall for them because the metal oil pan was rusting thru in the northern climates like where we are and leaving huge puddles of oil on the garage floor. Anyway, metal pans can rust, plastic pans can get damaged from road debris and so can metal so don't worry about it. Just keep the pan you got and enjoy the car.