Buying a Cossy is not like buying most normal cars and accurate history is very important. I am suprised that who ever you bought it from did not give you a detailed breakdown of what has been done to it. If you take it for a rolling road set-up whoever does it will need to know exactly how the engine has been built up or what modifications have been done. My advice would be to find a Cosworth specialist who can help you sort out the obvious problems and once that is done you will be able to enjoy driving it without having to worry about it running out of oil etc.