There's a ROM dump of the HP-35 version 2 (the one with bugs) available at my HP-35 page.
Seems to work fine with Nonpareil; Eric, feel free to add it
to the distribution if you think that buggy firmware is
appropriate to include.
The ROM chips are marked 1818-0006, 1818-0017, and 1818-0020.
Here's the errata list from HP---all the described bugs seem to be present.
It will be interesting to analyze the exp() bug---was it
an algorithmic error or merely a typo in some constant?
The trig bugs also involve arguments with 0.0002 or similar,
though, so maybe they're all CORDIC related.
Cheers,
Peter Monta