A full gasket set, oil pump, water pump, that's about it, but you can put the water pump on yourself and you really don't need it until the engine is done.
The bearings and rings will need to ordered after machine work. You may or may not need new pistons, it depends on if there is much of a ridge or if it can just take a hone job.
Thing is, if you'll wait until the machine work is done, you can sometimes either get a discount or save on or get free shipping since you're ording a big chunk at one time.