The choke marking is on the left rear of the barrel near the receiver. I recommend against modification other than preservation. The guns are great, and built well. So unless you're missing a lot of screws or have splits in the stock, it's likely safe to shoot, and use.
There seems to be a greater interest in these since Remington's break up. However the prices are generally still reasonable. I bought a couple 20ga models. One was so nasty looking I had my gunsmith reblue it. It wasn't a collectable, so just wanted it to feel nice, and look good.
I installed a Remington Supercell recoil pad. It isn't a perfect fit, but the Length of Pull is now correct and the pad reduces the recoil even it it's not beautiful... And it says Remington on the sides...

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You can see what it looked like before... it was Ugly! But now it feels like a new gun, and shoots great. I shoot skeet with it now and then and do quite well with it's MOD choke.