What kind of bikes have you been riding previously?
The reason I ask is that at 86CM PBH, you are probably "between" the 54 and 57.
If you walked into most shops, they would probably to put you on the smaller bike for all the reasons we fear most shops.
If you showed up in Walnut Creek and anyone at the RBWHQ&L got chatting with you, they'd likely encourage you to try the larger size.
Also, if you are going for upright bars, that might change the equation a bit.
If you are 5'11" with a true 86CM PBH, then you probably are a little longer in the upper body
You might call them in Walnut Creek and be honest about your budget restrictions and the fact you might not be buying it right away. They fit folks well.
J