The OEM part was most likely stamped steel 1010 cold rolled sheet. Typical hardness would be “Rockwell B” 60 with a yield strength of 44,000 psi.
304 stainless cold rolled sheet typical hardness would be Rockwell B 70 with a yield strength of 34,000 psi.
I’m assuming your looking at 16 ga (0.060”) material.
So what does this mean?
The sheet arch rail is dead soft as compared to the pinball (about as hard as you can get for steel).
Most ball arches I’ve seen (including the OP’s) have a burr or deformed metal where the contact pressure is max. This means that the arch metal is both wearing and yielding. Think of yielding like pushing your finger into playdoh. The playdoh just moves out of the way of your finger pressure. In the pinball v. arch case the rate of movement is extremely small for each hit.
In the OP’s photo there are two deformed spots (well probably more). The reason is that the ball is impacting the curved surface and rebounding in a straight line directly to the second deformed spot and so on. Eventually the ball will start a true roll along the curved arch.
So yield strength is important. 1010 stamped steel is 33% stronger than 304 SS.
The slightly elevated hardness of 304 over 1010 sheet is insignificant as compared to the pinball which is ultra-hard.
On the other hand most modern ramps are brushed stainless steel. What I don’t know is the stainless steel grade. 304 SS is the entry level and most widely available grade. There are many other SS grades that are harder and stronger.
The 304 stainless will most likely need to be a #4 brushed finish
The 1010 carbon steel will need to be chrome plated or at least painted.
Even with water jetting the ball rolling surface may need sanding.
All that said, 304 will most likely be fine for a home use application. For a game on route, maybe not.