So I can get a 90 dx for cheeeep.... swap b16a/18c?

Hey. I can get a 90dx that runs, but runs really really harshly. I don't know anything about engines or anything like that, but how much would a complete swap done by somebody else cost?

Power isn't that important, as long as it can keep up with my friend's RSX hehe.... (nah, just joking around... whatever's peppy that wont feel super sluggish)

Anyway... suggestions?