Conrod for 125 conversion

I bought a starstream crank to do the 125 conversion along with the barrel and head and have to replace the conrod. The 'MAZZUCCHELLI CON ROD KIT' on VE says it fits a Cento and Starstream...Anyone used one of these? We measured the existing conrod and the Mazzucchelli with a guage and they are slightly- 1mm or less- different.

if you can get the whole crank to chisel speed near Leeds, martin will split it and tell you exactly what's needed.
he did my vega crank with a Yamaha rod.

Thanks, but think it's going up to AFs with a load of other stuff