I doubt a 4.50 stroke will clear any hemi block w/ a 1/2" internal pick up. I raced a 426 for 14 years w/ a 1/2" pick up that I lengthened to fit a deep , long rear sump, hole for the tie rod type pan. A hemi has no more room that a 440 in there, and doubt weather the mega block does either, unless it a wider lower end version, and have never seen or heard of one except for fuel engines.....regardless of what ur engine builder says ! I have also never seen a gen 2 hemi block that the machine work wasn`t right on either !! But I`ve only had two.
A mega block bigger inside than a stock 426 block ?? The oil pump p/u boss in the block would not clear a 4.50 stroke .