What you have are two different stepping revisions of the same processor number (E5310).
I can only speak in general terms from an Intel server board perspective. Our processor population rules indicate when two processors are installed, both must be of identical revision, core voltage, and bus/core speed. We usually allow a +1 processor stepping difference to be compatible together.
For information on the processors you describe, see the Intel® Xeon® Processor E5310 specifications website and select the "Ordering / sSpecs / Steppings" in the left navigation bar. You'll see the B3 and G0 stepping processors that you have listed.
I strongly recommend checking with IBM to see if the processors you want to use can be used together in the system you have. There may also be BIOS requirements for the newer stepping processor to work in any event.
Thank you for the helpful information...