Ask Proudly for the .vmf instead of decompiling because recompiling a decompiled map leads to a lot of issues. If he doesn't have the original .vmf, decompile the map and remake all of the brushes with snap-to-grid on. And by doing this, you're basically making a new map so you should just rename it to something else.
If you look at the old insane asylum and compare it to the new version, you can see that the new one works with a layout that mimics the old one but is made from scratch.
Here are some pics of the changes for the asylums:
I honestly think the creator of the new version did a great job by adding some new assets, stretching the layout a bit, and revamping the lighting.
If you take the old infected hospital, retexture it, give it more props, and add a hallway or extra rooms, it's going to get the same complaints as the old version. This is definitely a project that would take a few weeks to create and finalize. Also, remove the ammo crates and health stations. I think these were the main reasons humans always survived and spawned-camped.
I will give you something later. For now, tone that erection down and wait.