Remember that 1 vCPU = 1 core.
Probably the guest will work better on Processor 8220 (cause has more MHz per core).
That is potentially true; however, remember that a MHz doesn't equal a MHz! If you compare older generation clock speeds to current generation clock speeds, there is a distinct possibility that you're comparing apples to oranges. The CPU vendors don't change ONLY clock speed when introducting a new processor - there are lots of other architectural changes that get thrown in for good measure. Things like deeper pipelines, bigger caches, more parallelism, etc. All these things contribute to the "speed" of the chip (not to mention differences in the speed of the FSB and RAM, better interconnects, etc.)
So - I'd say it's impossible to answer your question with any degree of certainty other than by testing your specific workload on each system and see which is faster 
Ken Cline
VMware vExpert 2009
VMware Communities User Moderator
Blogging at: http://KensVirtualReality.wordpress.com/
however, remember that a MHz doesn't equal a MHz!
Right, in fact I have write "with similar CPU architecture" 
And with similar I mean the similar number of pipelines, similar instructions, ...
Andre