With the Pb-Free BGA on there, you'll want to use pb-free solder paste for assembly. The logical course of action would be to use Pb-free solder paste for the entire assembly, and to reflow at the temperatures necessary for the BGA and Pb-free paste.
You may need to check the "standard" parts to insure that they can withstand the elevated reflow temperatures. When it comes to the actual solder connection, I would expect minimal issues between the Pb-free paste and the end caps of the components.
Then again, you should probably consider converting the entire BOM to lead-free. These days, Pb-free is the standard for the majority of the components on the market, and, most often, they cost less than the leaded parts. Unless there is some pressing reason to continue the assembly as 63/37, moving everything to lead-free is probably the way to go.
Cheers, ..rob
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