[truckster]

Since you're going to pull the oil pan, I would Plastigage the bottom end just to see where it's at. It's cheap insurance.

If you want to spend as little down time as possible, get the heads done first and have the parts on hand before you pull the engine. You'll need a temperature sending unit that will fit the Vortec heads - I got mine from board member A1971Blazer - he's a really nice guy (name is Whit) and he turns them down on a CNC machine.

As long as the bottom end checks out I wouldn't worry about putting new heads on that block.