With the thick aluminum rods you should check clearance against the camlobes. I am bulding a Hemi with Mopar rods in a Megablock, and 4.625 stroke, and had to slightly grind on the driver side rods (Eagle steel) in most advanced cam postion to make sure a thick lobed roller cam did not interfere. Less problem with a flat tappet I also mocked up. Interference point is on the rods where the threads exit. That is also a stressed part, so I do not know how much you can grind away if needed.....I highly recommend you check this first, to see if the alu rods will fit.