Irish rob

Hi , I'm logging in to help a friend who has bought a bike here in Ireland and doesn't know the model name, he can't get insurance without it and apparently it was imported from the us in 1997. I don't have a pic but am going to look at it tomorrow.It says its a Yamaha custom on the tank and its a 750, he recons it's a four pot inline and arranged from left to right while sitting on the bike.ITs a single seat and built/sold org in 1988... Straight bars and a fat rear tyre with a tight fitting mudguard. I know this may be a home made special but he's hoping its a prod bike for insurance reasons... Anyone know what model it may be by my hazy description....