B18C1 SWAP QUESTION>??

My Buddy Has A 90 Civic Dx 4 Dr . Has A B18ci To Install With Skunk 2 Intake Mani. Do We Have To Use The Integra Wiring Harness Throughout The 90 Civic?[ Replace The Whole Harness From Top To Bottom Cause He Has The Whole Harness Even Stuff Under Dash, Fusebox And Such],or Is There An Easier Way? Can We Use His Harness With Any Other Harness Kit?and Whats The Obd 1 And Ob2 Harness Stuff All About?any Help Would Be Appreciated Cuz We Want To Know Every Detail Before We Dive In . And One More Thing Do We Have To Use Integra Spindles For The C.v Jointsany Kind Of List On This Swap Would Be Great??yhank U