Purchase a Stage II engine block, which was not a "street" item at all.
See the tech info and photo guides elsewhere on this site. There are few parts at all that are the same between the OEM and Stage II blocks. Stage II blocks were used in Indy racing, Busch Cup racing, IMSA, and drag racing. The ports are huge compared with OEM blocks found in cars. Although they are much stronger, have much thicker walls and more head bolts to keep it together, no hard parts cross over.