Can you give a little more detail on the smoke? colour, density... are there any noises emitting from the engine that sound abnormal?... if so what are they. the more info the better, as nobody can give you an answer on what you have discribed.

also 120y's (sorry to the 120y fellows) were synonymous whith being the slowest car ever made.

as for engine convesions, what is your budget and what are you looking to achieve?