Looking at the install picture it looks like the 7502 is the easier board to solder to, is it possible you program the chip so I can do their 8-wire Stealth IV Playstation Modchip install?
thats from modchipoutlet which is based on their 8-wire Stealth IV Playstation Modchip
This is their details on that chip;
The Stealth IV ModChip will allow games that have Anti-Mod protection to play inside of a Stealth IV modified PlayStation. If you want the latest in ModChip technology and your machine is a model 550x, 700x, 750x, 900x, this is the modchip for you.
Also whats the difference between the 12c508a and the 12c509a pics?