Yes, you will need a wideband A/F if you are going to use the meter to tune the engine. The non-wideband type cycle between lean and rich when at idle or when cruising, peg at rich when at heavy/full throttle, and work better as fuel economy monitor than a tuning one.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed