From my armchair I have had fitted an old battery powered A/H on each instrument panel on my own ABs (they are cheap enough for me to have two). Whilst not as accurate as the full glass panel, working as it ought to. One or the other should be enough to to give me time to check the aircraft's pitch and bank
are not excessive, so I have time to check both my speed and altitude sufficiently adequately, using my GPS. And the check lists...
(We had to use the Astrocompass to check the compass's Deviation before we could land using the SBA. I cannot do that in my A or B, now.)
Some Tiger Moths had a spring loaded vane as an ASI. It was unheated.