g++-multilib conflicts with g++-4.8-multilib-powerpc-linux-gnu

Hello,

I'm setting up C++ compilers in Ubuntu 14.04 amd64.

I ran:
"sudo apt-get install build-essential"

That worked for the normal stuff, but I found it wasn't enough for a 32-bit compile:
"g++ -m32 hello_world.cpp -o hello_world"

To fix that, based on internet research, I installed the multilib:
"sudo apt-get install g++-multilib"

Then I wanted to compile for the powerpc architecture. Refer to <http://packages.ubuntu.com/source/trusty/gcc-4.8-powerpc-cross>:
"sudo apt-get install g++-4.8-powerpc-linux-gnu"

In the recommends section, apt recommends package g++-4.8-multilib-powerpc-linux-gnu.
"sudo apt-get install g++-4.8-multilib-powerpc-linux-gnu"

Apt then tells me that g++-multilib will be removed! If I do so, I can no longer compile hello_world on the amd64 machine.

Why do these two packages conflict with each other? I want to build 32-bit applications for powerpc. Doesn't that mean I should install g++-4.8-multilib-powerpc-linux-gnu? If not, what is that package for?

Is there a different way to configure my machine so that I can compile natively for 32 bit and cross to ppc32?

Thank you much for your help.