2012 KW T660 CM2250 engine swap into 2008 Pete 389 CM871

[Ctonn]

Have a rebuilt CM2250 in a 2012 KW T660 that was in a rollover, engine is good would like to swap it and put in a 2008 Pete 389 that has a CM871, it’s pushing coolant into the overflow. Haven’t opened it up to see if head, Head gasket or a dropped liner. Wondering if I would need a different wiring harness to swap the CM2250 from the 2012 T660 KW into the 2008 Pete 389 any help would be appreciated