[SiriusHardware]

That's another example of an Arduino Mega 'clone', yes. Other sellers and clones exist.

I do like those level converters you found as well, so it's up to you. I'm not personally aware of any PROM / EPROM reader software already available for the Pi, but I have not looked for it. I would be surprised if someone has not already done it and anyway, you may feel able to write something like that yourself since you are obviously somewhat familiar with the Pi.