150/152s "can" be used for instrument flying and teaching, but the preferred platform for both is a 172 as the cost difference is not much higher. Vintage Skyhawks with certifed GPS, GS, 2 VORs, maybe an ADF, 2 nav comms and possibly a DME start at about $40k. Then you have an airplane that is comfortable, safe, and flexible. With a 150 like you describe you will canceling IFR flights, and be nervous in IMC.