In my somewhat limited experience with plastic receivers, I found the lighter the sight, the better. One way to go is using aluminum mounts and the lightest scope possible within your budget. I have a Bug Buster that I'm sure would overtax the plastic dovetail unless the gun were really babied.I use a red dot whenever I can- first because I like them and tend to shoot well w/them, and second they're lighter than scopes. Obviously a red dot isn't normally going to offer any magnification so if that's a must-have, the red dot might not work so well for you.
Hi Mark what would be a good red dot for a 901? Thanks