95 Polaris Sportsman 400 rear spring/shock upgrade

Hey guys, I just got my first quad, a 95 Sportsman 400 4×4, and during it’s shake down run this weekend it seems like the rear suspension needs some help. I’m not a small guy (pushing 280 on a good day), and when I’m riding the back end seems to sag more than it should, even with the preload adjusted to the highest setting. The assembly looks all original, and the shock bushings are pretty clapped out, so I’d like to replace it, but I’d like to replace the spring as well. It looks like Polaris is no longer making replacement springs for this model (part# 7041299-067), and I haven’t been able to find anything in the aftermarket that is compatible with my specific sportsman. The ones that show up on ebay looks just as bad as the one I’ve got on there, so I’m not sure if that would be any better.

Really I’d like to throw something like a Bronco strut assembly (one that includes the shock and spring in one unit), but they don’t list anything that’s compatible.

Anyone have any experience with this? Thanks in advance.