I used a probe kit. It costs about $1000.00 for 60 over forged pistons, forged h rods , probe crank and rings and berrings yelds 402 with no block modifcation. 427 kit from powerhouse (
www.enginekits.com) $845.00 requires block modifcation. I like the way mine turned out, burns rubber in second with out dumping the clutch. good luck.