Well yes and no..... the timing cover is aluminum. When in the presence of iron, all the corrosion will be on the AL part. So the cover could be really bad and the block situation be less bad. But, yes, the blocks and heads should be flushed out and cleaned out very well; it just may be doable without full dissassembly. I'd pull the block drain plugs and if they were blocked up on the inside, THEN yeah the blockages there are indeed pretty bad. Either way, then do the muratic acid treatment as a first try. (Just seeing if the situation can be salvaged without a full teardown; I cleaned out a /6 acceptably well that was this bad and got past it's heating issues.)
