You have to remove the belt pulley and HB to get the timing cover off. There are lots of "gotcha" bolts. Look at the manual to know where to expect the timing cover bolts. Two behind the IP gear to the block I recall. The hardest are the little ones in the oil pan. The biggest leak chance is the corners of the oil pan, block, and timing cover. GM bolted every damn thing they could to the water pump on this engine. But once it's off it's really not far to the chain.
The bypass hose to the T-Stat is almost easier to pull the crossover off to fit that hose on...
You need the HB puller. The lower timing sprocket may be stubborn. The cam and crank sprocket come off at the same time. A new chain will be tight - normal.
The Right Stuff with gaskets should work. I have used high temp RTV. Note the timing cover is a mess to seal up with the water pump outlets going through it. I have used the gaskets with RTV on both sides of the gaskets.