If you want it accurate - wideband.
If you want to make it as close to 14.7:1 as you can, go narrowband. Wont help you if you're trying to tune closed loop.

Look for an AEM UEGO wideband... usually can find for $150 bux... or check the classifieds on customtacos.com or yotatech for a good used wideband...

89 4Runner
3" BL, M/T locks, 33"bfg mt, bilstein, Kayline, tubebumper, toyotafiberglass panels
TBI: Elocker,3.4 w/ORS,b+b,S2Sstg2cams,arias pistons,P+P intake,TRDs/c,URDpullies+7th,downey headers,MAPECU2,WEGO WB, SupraMAF,walboro255,stg4clutch, EPaOo2 sim