AUB crankshaft replacement

[AUB1416]

Hello people. I have an aub 1.4 engine (16V 101PS) and I am thunking about fitting the bottom end (crank, rods and pistons) from a 1.6 polo gti engine. I have read somewhere though that it is impossible to unbolt the crankshaft from an aub engine as if you do that the block destorts. Can anybody confirm or deny this as I have only found one other reference? 

 

Thanks in advance