Hello, 
I´ve got a small Pillbox Hill Medical Center to California Hospital Medical Center transformation pack for you.

Installation: 
1. Open OpenIV and enable edit mode.
2. Go to C:\Games\Grand Theft Auto V\mods\x64i.rpf\levels\gta5\_citye\downtown_01\dt1_06.rpf\
and replace all files except the dt1_lod_emissive_6_19_children.ytd file
This file comes into this path: C:\Games\Grand Theft Auto V\mods\x64i.rpf\levels\gta5\_citye\downtown_01\downtown.rpf\

3. Enjoy it.

It´s highly recommended to backup your files before doing any changes.

All the best, Michael : o )