Two more screens press into place from the front of the block. They allow oil to lubricate the timing chain.
While you are still working on the top side of the block, use a tap to clean the head bolt holes. Many magazines say you must use a thread chaser and not a tap. It's a nice idea, but most of us don't own a set of thread chasers. If you are careful, a tap will work fine. The idea is to make sure all the holes are clean and none of the threads are damaged so that you will get proper loading on the cylinder heads when you torque the head bolts into place.
This step should be done after all the original oil gallery plugs have been removed and all machine work has been completed, but before the new pipe plugs have been installed. Don't depend on washing the block to remove all dirt and debris. You must clean every oil gallery in the block with a brush to remove all the dirt, rust, and metal debris. Many racers forget the galleries that feed oil to the main bearings from the cam tunnel. Many companies, such as Powerhouse Products, sell inexpensive brush sets designed to help you reach and properly clean every gallery.
Use a die grinder to chamfer the bottom edges of the cylinder bores. This can be done before the block is bored and honed. Doing this doesn't harm power and keeps the engine from shaving off slivers of the piston skirts on sharp edges at the bottom of the cylinder bores.
You probably aren't going to use a dipstick, so fill the dipstick hole so you won't forget about it later. Good old silicone works well here.
When you are ready to begin final assembly, it is time to install the freeze plugs. Remember, all freeze plugs aren't created equally. Spend an extra buck or two for a set of deep-cup freeze plugs, which seal against the block better and are less likely to leak. Most racers use pure water for coolant, so it is also a good idea to get brass freeze plugs, which do not rust. As cheap insurance, red thread sealant not only helps lock the plugs into place, but also seals well.