OK, two things are happening that haven't been addresses here. First, there are two different thicknesses of front pan seal on 350's, and the 1-piece gasket only works with one of them, the thin one, I think. Take that 1-piece thing out, and pitch it as far as you can throw it! There are certain years of coverage where the gasket set will have two different front seals, and a measurement specification for which one to use with your pan. Glue the correct end seal to the timing cover with yellow trim cement to keep it in place while you install the pan, and use a small quantity of RTV rubber sealer at the joint where the cork side gaskets meet the rubber ends. Tighten the bolts only until they're slightly snug, then go 1/2 turn more. DON'T overtighten the bolts until the gasket bulges!
Second problem- - - -the timing cover seal runs against the harmonic balancer, not the crankshaft. If there's a wear groove there, there's a repair part called a "speedy sleeve" that can be pressed over the balancer snout to cover the groove. It's stainless steel, so it lasts much longer than the soft steel surface of the original balancer surface. Be careful installing the sleeve, it's pretty fragile.
Oil pan sealing is very unforgiving of mistakes. You've only got one chance to do it right!
Jerry
