M52 diff ratio

[Matt316touring]

Hi I’m fitting a 2.8 m52 (around 240bhp) into my 316 touring , it has the 325i 260 box and prop which diff do I need as it has the standard 316 at the moment, I do have a z3 1.9 diff is this any good ?

[HRH-squidlips_III]

arround 3.64 is what your after a z3 diff is 3.38 a little tall for arround town but perfect for the motorway will be small case though at the limit for 240hp