Need HELP! with brake question

[ScottH]

I have a 65 Chevy G10 van I'm in the process of working on to get it road worthy. Most of the work is done with the exception of the brakes. The fronts are stock 9.5 x 2.5 drums but it looks like the rear might have been changed. The stock size for the rear drums are either 9.5 x 2.5 or 9.5 x 2, depending on which rear was installed at the factory.

The rear drums on the posi rear now in the van are 11 x 2. From running the numbers off the wheel cylinders, it appears that the rear was from a 66 and up full size GM car, like an Impala.

So my question to our brake gurus is am I going to have problems with the rear drums/shoes being larger than the fronts? Keep in mind this is a single master cylinder system.

Any info, suggestions, or opinions would be greatly appreciated!

Thanks.

Scott