best bang for the buck swap, H22. this one also has some clearance issues as it is a much taller motor than a b-series. but this swap can be done at a MUUCH more reasonable price than a K. you get 220hp right out of the box, which is MORE than the K. i think the K has it in torque though, but not sure considering the displacement (H22 = 2.2l) (K20 2.0l) K24 =2.4l
not long after the K came out, they started frankensteining those motors as well. now if you want real NA power/torque, you go with a K24 block (for the extra displacement/torque) with a K20 head for the top end power. a modern day LS vtec, as most vehicles that came with K24's didn't have VTEC (well, i-VTEC now). i might be wrong on that one though so DON'T quote me on it.