Looks like an auto ranging circuit would be needed to switch the VTVM to a higher voltage.

That means like a lm3914 in dot mode with one dot set to like 15.05 vdc that dot driving an cd4066 analog switch to the 1,500vdc scale.
I'll have to figure the input Z of the lm3914 circuit to fit it in the HV voltage divider. Just hope the 50ua meter movement is slower than the lm3914 and cd4066.

73 de n8zu