Why is anyone hung up on having a roller block? Sure they take factory roller lifters. But they are no stronger, may have cracks (see the PSA sticky), and people think they are worth more. But if you pay less and don't have to worry that the block might have cam tunnel cracks and you can find one more easily (you can as they made way more non-rollers), you can run link bar lifters and be on your way.
At this point in my growth of knowledge, I'd choose a non-roller block first and foremost. Because buying a roller block and having it checked for cracks to maybe have it have cracks and junk it to have to go buy another and repeat costs time, money and effort to locate engines. Time = money and potential aggravation. Seems worth it to me to skip all that. The difference is 2-300 bucks more and in the total picture of dollars spent to build an engine, an extra 2-300 bucks is not a lot. You'll likely spent 25 times that building the engine.
Looks like any E4 or newer block should have the one piece rear main seal from some searching. E4 being on the bubble, it's be worth checking before buying. The E5 or E9 are well after the change over date.
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