Just thought I would share this with anyone who might be interested. The guts of a PAL RF converted Core Grafx.
I tested it and it did work and the image was actually not terrible, although obviously being in 50hz the games were slower and had a floaty feel but the colours were nice and bold.
I decided to remove the "mod" and return it to its original fully functioning state with an RGB mod (see bottom photo).
Apart from replacing the AV socket the only other parts that had to be replaced were the 470uF cap (next to AV socket) and the enormous 2200uF cap near the voltage regulator was removed and returned to normal. I also did the jailbar fix using 4.7uF surface mount caps on the underside.