Fastest for the least would probably be a 1.8L non-vtec engine from an Integra RS GS or LS, with a turbo.
Otherwise an Integra GSR or Integra Type R engines are going to be the fastest swap-in without any other work engines.
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-Harry
AIM: NDcissive
CRX and Pre '92 Civic, Engine Tech and Tuning, & Track and Autocross Forum Mod