Thanks.  The posting, and reading replies, gave me enough time to calm down and think rationally.  After spending some time putting on the second set of hydraulic lines and chasing the manifold mounting stud holes, it was a little irritating to find I had the "wrong" head on my engine.  I decided it probably would work, but it sure is nice to have someone else with lots more Oliver experience tell me that!

I have to put in a plug for Jerry at Ag Parts First.  I called with the numbers off the old manifolds and he checked them to find they were 88/880 parts.  I told him we had a problem as I had already painted the new manifolds (I know, should have checked to see that they fit first, but my other old tractors were not as adaptable as the Oliver and a part for an M or ZB was never a problem like this).  Jerry said no problem, he'd send out the proper manifolds today and I could send back the 77 set.  He said he'd issue a credit when he got them as the 88 manifolds are less expensive.  Not used to that sort of service these days!  Jerry is related to the former owner of Rick's Ag parts and he absorbed that business into his.  Good outfit to do business with, IMHO.

Ed