Charmer,
Check out the FE Forum on the main page. Under that, is a thread call FE Block Numbers started by me. That's how I ID'ed my engine.
Actually, side oiler service blocks were manufactured through Sept. '72, and they were all hydraulic lifter blocks between 68-72. I finally deciphered my date codes that I referred to earlier above the
oil pan, as July 3 or 8, 1971. You're completely right about the conversion to solid lifters, which mine now has.
Again, it doesn't mean that it's not a nice side-oiler and worth the money. At any rate, you might find that thread useful.