It is a 170, not 140, but the lack of a backup to the one gyro is a no go for me. I have done plenty of partial with only turn and bank, comfortable with that. In my many years of flight, I have had about 4 gyro failures while flying. With 3 gyro's, that is a non event.
At less than 200 hours in my logbook, I flew into zero visibility at 7,500 feet on V3 west of Richmond Va. The forecast was 12,000 overcast, 10 miles viz below, from 3 separate briefings, 3 hours apart, 3 widely separate FSS's, one face to face. That leg of the trip was 2 hours after sundown. Failure of the single gyro would have been a disaster, but with 3, no worries.
At 3,500, out of the wet snow, in rain, and VFR again, all went fine. Visdibility was way less than 10 miles, but ground lights were there to see. I coordinated my descent with ATC, no clearance allowed for VFR flights, but nice to know for sure that there were no planes below me. Stayed centered on V3, wings level, and standard rate descent, no sweat. My instructor had gone above and beyond in my voluntary instrument training.
Back to that beautify example of Cessna 170's, perfect for a second plane for someone who can afford to keep it in a hanger for daytime flying, in perfect weather, it is a classic museum piece. Adding modern electronics to the panel would destroy much of its present value. That full size clock is a rare device in a general aviation aircraft, I have never seen one before.
The hand held electronic devices could be used for synthetic gyro instruments, but my trust in them is shaky, mine do go blank at inopportune times, plus, you would need a separate power supply with sufficient duration to cover at least twice the endurance of the fuel tanks. The only aircraft that I have flown with less instrumentation were the Piper J3's with no electricity, and no gyro's.
If yu do buy that plane, I would love a flight in it!