You can use scotch brite for cleaning the block. I use a razor and take my sweet time making not to nick the aluminum. You can reuse the tensioner. If the idler pulleys are making noise, replace them. Some people replace them just to make sure, some also replace the water pump since it a slight pain to get back in there should it fail, but few do fail.
Head bolts are reusable in my experience. Check the rear main seal and the funky shaped access cover for leaking, re-seal as necessary. You could open up the exhaust ports and match up to the headers while it's all out. You can chase all the threads to make sure they're all clean for reassembly.