Will a 1972/3 LT2 100cc engine bolt into a RD60 frame without modifying the frame. I have a 1980 GT80 engine that I am going to bolt in because its a bolt swap but was just offered a LT2 engine but do not know if it is a direct swap, I'm of the opinion it isn't. I do not want to molest the frame because it has a matching numbers newly rebuilt engine and the entire bike only has 900+ miles on it plus we've had it maybe 20 years or more. I have 1974/5 MX100 engines and they will not bolt in but I think the bottom end cases of the LT2 is an older design. Thanks in advance.