Yes there should be a tube from the engine block to the pressure gauge,the tach should be a grey wire coming from control box or directly off engine if equipped if not find the tack hook up on the ignition box,if there is a cover on it it may show a diagram,that wire goes to the sender stud on the tach,should then be a pos and neg stud,neg is ground,hook the posi wire so it is hot when you turn on key switch,make sure the adjustment on the back of the tach is set for that motor.
get a repair manual with wiring harness diagram in it and it is very easy. good luck