I sure hope you understand what OBD's are.
your 91 Is the last year Honda/Acura made cars in OBD0 form... yoru 98 LS engien is OBD2... common sense says becuase the numbers following OBD are different that you cannot use the electronics, Intake Manifold yes, injectors no.
Just Wire the engine OBD0 using your stock LS harness, ECU, distributor, injectors & Throttle Body.
pre88-91 = OBD)
92-95 = OBD1
96-Present = OBD2A-B