Personally I think the aluminized wings are not as nice as the fabric ones, either in look or flying feel. Also, there were something like six different STCs used to aluminize the wings, some of which require the drag wires to be present, and some which may permit their removal. An aircraft without drag wires with a STC that requires them would not be airworthy. In any case, really look at the quality of the metallization, since I've seen wide variations, as well as wing-to-wing variations when a couple guys took one wing home each for a winter and did there thing. Really.
That said, 120/140s are about the best flying aircraft Cessna made. A well rigged one is a finger tip control aircraft and the trim is very effective and very sensitive. They will also handle substantial amounts of crosswind, often more than their bigger brother four seat Cessna taildraggers.
The C-90 engine is a nice compromise between the C-85 and the O-200 conversion. Personally like the stroked C-85 (change crank, rods, and pistons to O-200 parts) best as it is very torquey. Sadly have flown many versions, but none with C-90 but have heard that it is very close to the stroked C-85. With a stroked engine, and possibly the C-90, the standard 71/48 prop behaves more like a climb prop. So you may already be there with the airplane in question, but depends on the pitch.
The 140 outsold the 120 3:1, but it carries 22-25# of flap weight that really don't do much. While prefer the 120, 140s are about as nice. Most 120s have been modded into almost 140s with the addition of electrical systems, d-windows, interiors, etc. Just no flaps.
Not a fan of the gear extenders. They could be added to move the gear axles 3.5" or so forward, allowing for a less tippy airplane. However, they also exert a moment about the gear box and mounting bolt that seems less than great, though many have had them for years. The first year and a half or so models had "straight" gear - they are no more "bouncy" than any other spring gear Cessna taildragger, but they do have the most forward c.g., making them the tippiest (without extenders). Later the gear legs were swept forward, effectively putting the effect of the extenders into the gear itself. There's a reason the landing checklist has an item "feet on the floor." The earlier ones tipping tendency is also accentuated by having cast rather than stamped rudder pedals - the stamped ones pivot point is lower down, making it easier to get inadvertent braking. But again, practice, slow increase in winds, and proficiency make all this moot. Routinely land them in 15 knots direct; have done more from time to time.
The gear boxes must be inspected for cracking. Also, the door post is a multi-layer riveted construct that may crack. Both may be very difficult and expensive to repair. Most have Scott 3200 tailwheel and may or may not chatter at higher speeds. Shims can help to set angles correctly. Tail in generally takes a bit of a beating like all tailwheel aircraft, but this one sits very low to the ground, so there are both debris and condensation issues (corrosion) to look for. Cessna120140 Assoc. has wealth of knowledge.