Engine problems need help quickly

[garboi1234]

car=golf mk2 driver 1.6 pierburg carb
engine overheated due to a cracked water coupling on the front of the block cracked(the one withe the wired connected to it,which has the radiator pipe joining) causing it to over heat. now i have problems with white dry smoke from my exhaust. this only occurs when idling and acceleration from gears 1-3. crusing no probs. me and my dad fink its a blown headgasket or fried pistons rings.
any one got any ideas?

[mk1]

If it is still loosing coolant and the exhaust fumes have a sweet smell, it does sound like a head gasket fault .
Steve.