Oops, you're right. Most sources list g/cm^3, but you're correct that the raws use kg/m^3 (and 430 kg/m^3 is the proper figure).

Ah, yeah. Saguaro wood probably floats, and the cutoff for that is below 1 g/cm

There is at least one wood that does not float: ironwood.

It's only thanks to DF that I know things like this.

“Ironwood” is a name used for a whole bunch of different unrelated tree species.

I believe lignum vitae is just about the densest commercially available wood. Definitely sinks.

The nice thing about the DF raws is that they now list the actual species used as a basis. A lot of research went on some time ago to add correct, sourced information to the raws. There are probably still a few wonky things, as some of the properties in there make more sense for metals than things like wood, but the players care about even strange details like that.