You might be able to find additional RGB TV modding information for that particular CRT at either
CRT Gaming Subreddit or
shmups.system11 forums. As krssn said, you should always discharge the CRT before doing any servicing/modding and only if you really know what you are doing. Recall that CRTs can have a capacitance in the
multiple Farad range (high enough to hold a charge for years and kill you).
If no RGB mods are available, I'd keep an eye out for either a cheap moddable CRT, a Sony BVM/PVM, or an IDC34 RGB Multi Input monitor. Sony BVM/PVM CRTs have BNC connectors for RGBs/RGBHV inputs, while IDC34 monitors (such as the Sony ProFeel KX-2501a or certain NEC monitors) have a proprietary IDC34 floppy port. This port has all of the signals available for a RGB setup, and a DIY circuit can be created to
interface SCART or
BNC (RGBHV+RCA Audio) to the floppy port.
I have a Sony KX-2501a that I found for dirt cheap, and RGB works spectacularly with such an interface circuit.