i had to change the cam in my 350 and need to put the timing cover back on, but am unsure of the best way to do it without it leaking. Anybody got any tips or comments on the best way to do this?

Use a new gasket or 100% silicone

Get one side of the cover on its locator pin and push the other side of the cover down by taking a drift and putting it thru a hole in the cover and that cover hole in its corresponding hole in the block. Pry downward at the same time you push the cover towards the block. With enough patience and fortitude you'll compress the rubber bottom cover gasket to get the other side of the cover to drop onto its locator pin. After thats done, bolt her up.

Obviously this assumes that you have not removed the oil pan.

When you get the cover back on I would suggest that you place a bead of silicone all the way around the front cover where it interfaces with the block and the oil pan as insurance against leakage. Just wipe it on with your finger and remember that any silicone that does more than seal that interface is wasted silicone. :)

I just went through this drill on my 396, a little different situation cover wise but I would STRONGLY recommend buying a can of Right Stuff from NAPA or who ever, make by Permatex Folks, make sure ever thing is very clean, you check this by using masking tape, if it sticks you are clean enough. If you use it right and let it sit for 24 hours or so, you will be good to go.

Jesse