windowlicker

have you burnt the new plug out? Check to see if it glows up properly and the end is not black. Are you sure your temp gun is accurate, does it need new batteries? 329 sounds very high esp if there is good smoke. You weren't thrashing it at WOT were you?!

All I can think of is maybe the high temperatures caused a seal or gasket to blow. Check there is no oil being squirted out of the exhaust gasket, the carb, or the front seal. Check the engine head it tightly screwed down with loctite. You may have to get some silicon sealant (high temperature car stuff) and seal your engine if it is an air leak.