I'm running a 15x7 rim all the way around on the car in my sig.

P235/R6015, 26.1" tire up front
P255/70R15 29.04" tire out back
I have 4:10 gear and IIRC I have a 39 tooth speedo gear.

IMHO 14"s are a bit too small, but it's your overall tire size that's a tad short.
Your rear tires will look like my fronts...

Your 235/60 = a 25.1" tire, with 3:55's you will want a 36-39 tooth speedo according to the chart in the archives...