I have a '74 1800cc  It sounds tight but burns considerable oil.  runs 
a bit rough and misses intermittently. all plugs are fouled.  
comments on what may cause this? maybee I need a rebuild.  Does 
anyone know approx. how much the parts will cost individually/as a 
kit?  would it be wise to just do the upper end?  any other 
suggestions?   thanx