I could be wrong, but that sounds like a cracked head. I was looking at buying a raider with the same problem (coolant out of the exhaust) and this was the culprit.

I had a head gasket problem a while back which was a pickle to diagnose (sounded like a harley-davidson) with no loss of coolant or mixing in the oil. Turned out the head gasket gave up on the number 3 cylinder. Put on a spare head I had from my 87, a new Felpro head gasket and no problems since.

Hope this helps. Sorry to hear about your troubles.

'88 Raider 2.6L - SW Hubs, Weber 32/36, Off-road Pkg - Dead
'88 Monty 2.7L - 5" Lift, Weber 38, 33's, Dual Fans, Dual bouncy (more goodies to install) - Still Kicking.
'03 Monty Sport - XLS, BFG A/T's - Dead