I would. I would do it to spread the load and also because the timing cover is aluminum. Washers will help keep the bolt heads from chewing into the soft aluminum timing cover. Don't forget to coat the threads that go into the water jacket with RTV and also the four long bolt shafts with RTV. If you don't do those four, they will corrode to the holes in the timing cover and break off next time you try to take them out. Lastly, be REALLY careful with one of the bolts on the driver's side of the block. It is pretty shallow and backs up against #1 cylinder. If you use a bolt that's too long there, you will run the bolt right into #1 cylinder and crack the block. That will suck. So figure out which bolt hole that is and make sure not to use a bolt that's too long. I cannot remember which hole it is, but if you pay attention, it's pretty obvious. As a rule though, I put RTV on the threads on all those bolts whether they hit water or not, because it also acts as an anti seize and they come right back out next time.
