If I remember right, the bottom of the grip frame should have offset holes, right? You can get one of these to use any bottomline on the market: http://www.sundragonpps.com/catalog/...90/5025303.htm
I highly recommend a rail and a CP on/off ASA, but with how far the adapter block's dropping it down I would also suggest a direct mount CP.
Tank... depends on your budget. If you're a person who plans on playing with this marker every weekend at a field with air fills, then perhaps an HPA would be for you. They require recertification every so often, however, just like CO2 tanks, and are costly. CO2 works alright when warm, excellent when you're being baked alive, and just plain "meh" when it's cold. HPA is the same all the time. It's all up to you.
Hopper... get a nice cheap Revolution (fondly known as the Revvy) from any paintball forum used. They last forever.
Great price on a classic, btw.