There is a 18RG car in my workshop now, with 11111-88231 head. So I would have thought the 88250 was a later model with lower compression. Either way it makes little difference. The pistons may have been changed, and any air injection or EGR it once had would have been removed long ago. What does matter is the results from your comression test. If you are keen, get the starter on it and crank to check compression. If the engine has been sitting around, the carbies probably need to be pulled off, checked out, and re-sealed.