Need help on Turbocharging a 318

So ive recently bought a turbo setup, and had some questions for all you turbo people.. Its a garret t3 turbo, it came with a bunch of tubing, an intercooler, a blow off valve and clamps lines n such.. So i wanted to know is this turbo set up okay for a 318? Or is it on the small side, would i benefit from a twin turbo setup, using the same turbos like say two t3 garrets? Or would i be okay using one turbo?.. As for what im looking to get out of it, i would like maybe 400 hp or so. somewhere in that neighborhood. Its for a 72 dart swinger if that matters,... Besides for 100 bucks i just couldnt pass it up lol, i had to and ive always wanted a turbo set up haha.. Also when people say shaft play, is that the compressor that has play or not? Sorry for the long post, any helps is greatly appreciated. Thanks!