The Maverick 88 is an excellent little pump gun. I have one myself.
Every part that fits a Mossberg 500 is interchangeable with the Maverick EXCEPT the trigger assembly, as the safety is a cross trigger type instead of a topside slide safety.
I actually prefer the Maverick's safety to the Mossberg 500's. When I was in the Navy, and had the M500 slung, the safety was always getting knocked off by things on my belt, never had that issue with my Maverick.
You also want to look at the manufacture date, I'm not sure of the year they changed it, but the older models only had one bar from the pump grip into the receiver, newer models have two, like the M500.
Overall, a very inexpensive pump gun that will last you a very long time if you take care of it.