How far do you plan to go with this reseal? If you plan to literally replace every gasket and seal in the engine, I recommend a Fel-Pro engine gasket set. If that set comes with a Teflon (PTFE) rear main seal, do yourself and get a standard nitrite rubber seal to use instead.
The biggest factor will be surface prep. Make sure that both surfaces are absolutely clean and do not have any burrs. Then take a straight edge and make sure that the surfaces are flat. Lay a uniform bead of rtv all around the sealing surface of the part that is going onto the engine. Make sure to tighten the bolts uniformly and in a criss cross pattern. Do not over tighten! Snug it down but don't monkey nut them down. If they are too tight they will warp the part and it won't sesl.
I can not stress how important those first two sentences are. As for RTV, it is okay to use, but it is best used sparingly unless otherwise called for. Most places you will use it need a skim coat at most. Apply just enough to help seal, but no enough that it'll squeeze out everywhere once bolts are tightened. Modern gasket sets have greatly cut down on the amount of RTV needed to seal a block. A little is needed on the oil pan gasket at the corners where the block meats the main cap. Depending on the gasket style the intake manifold gasket gets RTV at the front and rear of the valley. Doesn't hurt to put a little on the outside diameter of the rear main. That's about all that needs the stuff. The good oil pan gaskets and valve cover gaskets that they have out now are very good at doing their job without any RTV.
Before reassembly check out the condition of the sealing flanges on your oil pan and valve covers. If they are beat all to hell it won't matter what gaskets or RTV you put on they will go back to leaking. If they are rough it might be worth your time trying to straighten them out some or getting replacements.
Other thing I'll add to this is invest in a torque wrench. I don't care how well calibrated your wrist is, it's not good enough to get an even and proper torque on the bolts that need it. Torque anywhere that there is a gasket, which pretty much means torque everything.
3M Super Weatherstrip Adhesive. been using it for the last 30 years. Works great. I have assembled complete engines using it. An old automotive machinist turned me onto it.
If an old automotive machinist told me that I'd never set foot in his door again, and would ignore pretty much anything he told me from that point on. 3M makes great stuff and I'm sure their Super Weatherstrip Adhesive is great at what it was designed for, but that was holding weather strip in place against wind, rain, humidity, and 125 degree weather. It was not made for withstanding prolonged contact with hot motor oils, on an engine that reaches temperatures of 300 degrees plus (engine temp, not coolant temp). If you must use something to hold a gasket in place use a skim coat of RTV that was made for the purpose, it's really not that expensive and a small tube will do a motor.
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