Where is the pinhole leak? I can't imagine changing the block for a small leak and I can't think of where it would be leaking on the block. If you have a blown head gasket it could leak water into a cyl but the you just get the head milled and put on a new gasket.
4" Teraflex long arm lift. D30 tubed with chromoly axles, high pinion, powertrax no-slip and Warn Lockout Hubs. D35 w/ultimate 35 upgrade OX locker, 4.56 gears. NP231HD, Air on Board, Warn M8000 Winch.