Some times on a well worn engine it's better to trade in the core on a Re-maned Built Shorts Block . There was a Place out by me called the Chevy Shop . I sold that Guy a Few Short Block cores that needed to be Bored out . He had a Floor Full of Built up Short Blocks all Bagged up read to go . From Bored out 305's to 454 SB's 2-Bolts- 4-Bolts you name it . And for cheaper then it would Cost you to have one Built . 355 4-Bolt Mains with hyper Pistons Rebuilt Rods decked Aligned Bored with HV oil pump and Hardened Shaft $700.00 OEM Rollers and Early Gen 1 Blocks .