I would NOT completely redo the fuel system. I just bought all the stuff to redo mine (fuel cell, fittings, new pump and filters, regulator, etc) and I spent about $800, and that was buying all the cheap stuff. I bought hose barbs and rubber hose, not AN fittings, and saved about $300 by doing so.
For FI you can run the stock tank with a small surge tank (search it, there are some good threads on surge tanks). You can buy one or make your own, they're easy to do, and then you don't have to worry about a fuel cell. My fuel cell, by the way, is probably 20 lbs HEAVIER than the stock tank.
For my $$$ V8 is the way to go. Easy to find parts for, cheap to make big power, and enough people have done it that you won't be struggling if you hit a stumbling block along the way.