I've got a modern PC that that has absolutely no parallel port at all. Have you figured out yet how to get a USB to LPT converter working yet? Maybe there's some hacked driver you can use for such converters, in place of the manufacturer's drivers, that causes them to much more thoroughly emulate a true parallel port?
I also noticed that you mentioned the problem with newer Game Sharks is that they have missing the serial to parallel converter. If at any point in the cartridge there is a serial signal rather than parallel, then maybe I could cut an RS-232 serial cable in half, solder the wires on the cut end to the board of the Game Shark, and plug the other end into my USB to Serial converter, and then use it on my PC that way (after reverse engineering the protocol, and writing my own custom software to communicate with the Game Shark.
There is one more problem. Game sharks are EXTREMELY prone to failure. I have had 2 Game Shark Pros in my life. They both had a 100% failure, an utterly complete failure. Not even their boot screen would load after failure. The screen was completely black, as if the firmware/bios in it had been completely wiped out. The first one failed after about 2 days. The second one failed after about 1 month. These things were so crappy, that I didn't waste my time buying a third one. I figured that if the company that makes them puts out such horrible quality products, then it's not likely that they will change their manufacturing process to make it any better. They just do stuff the quick cheap way, and I'm not going to buy anything else from them. At least that's what I thought, until I learned just now that they can be used for something far more impressive than cheating. They can be used for dumping games. If you need it for cheating, you need it every time you play the game, but if you use it for ROM dumping, then you only need it working for a short time, so that you can dump your games. If it spontaneously self destructs after this, it doesn't matter, because it was only needed to work for a limited time. However, if anybody has any idea what causes these failures, and knows a fix (like soldering on a different value of resistor somewhere to prevent damage, because the manufacturers commonly used the wrong resistor size somewhere or something), then please let me know.