I'm planning to re-use a set of Zapp SY60 3nm motors, 68V linear power supply and analogue drivers which should do for starters, then, and I'll see how it goes. Can always add another motor if needed.
This whole design process is interesting: we are urged to study, analyse, carefully consider. I used the spreadsheet to get better insight into motor sizing but the answer, in practice, comes down to "SY23 because SY17 are too small, SY34 are too high inductance, and you might as well go for 3nm as they cost barely any more than the lower power motors in that frame size." Power supply sizing is similar.
Ian - you could look at the Zapp web site for a kit. The price (at least when I bought) is the same as buying the individual parts but at least someone has identified a bunch of bits that play well together.