You probably can compile just fine on a 32 bit system, so ignore the comments about trashing your machine or updating beyond it's capility. 64 bit code takes about twice as much as 32 (less, but you can disable some features). In many cases Chromium can be compiled setting I_KNOW_WHAT_I_AM_DOING="yes" on same line as emerge. Some programs don't have this feature (Rust I think ia lacking it). It unfortunate as it makes Gentoo/Funtoo less likely to be systen of choice on embedded systems, where the finished system really shows its strength.