mazdatweaker_2
+1y
From reading your posts it sounds like it started out as an '89 and a '91 short block was swapped in (under the head) and the engine is still carbureted. It seems like a lot of work to convert one of these trucks over to Fi, but who knows what the history is. That being said, since you have the head off there are a couple of things you can look at / for. There are supposed to be two dowel pins in the block to center the head gasket on the block. If either or both of the dowel pins are missing, that might be how the head gasket got mangled over time, because it would have been free to move around on the block deck. So maybe oil could have been being sucked in past the sealing rings. Can you post any pictures of the parts like the pistons or the block deck you are talking about?
As fas as your question as to getting a correct replacement part is concerned, I don't think there are any differences between the short blocks between the Fi and carbureted trucks, but if you have a concern about that, there is a spot on the right front corner of the block that carries a block stamp and you could take that number to a dealership and probably get whatever question you have answered.
You are right about doing the rings; it is just a matter of pushing the rods out through the top of the block and I would recommend doing that job while the head is off; otherwise I think you are going to see lots more smoke without doing that part of the rebuild. Make sure to mark the cylinders the rods come out of and rod direction. You could just throw a head gasket on it and hope that takes are of the oil burning but oil burning in these tractor engines is almost always due to worn out oil control rings.
Hope this helps.