I am contemplating an engine rebuild for my 1973 MGB (Noth American Spec). The engine serial number is "18GH - RWE - H38831". According to my limited research the motor ssems to be a 1969 (18GH) high compression unit (H) which originally came with O/D (RWE). I have owned the car (non O/D) since 1983 so somewhere in it's early history it appears to have had an engine transplant. Anyone who can confirm this would be appreciated.
Thanks