I went through this three different times Bob and have some differences from Brent's excellent system that have worked for me. Be prepared for work though.
First off-every
oil pan should have a billet block rail. Then there'd be even clamping. I think only Aviads do. All the steel pans have those lousy flutes.
To that end I trued my Canton by hammer into a roughly flat flange. Then filled the flutes with JB Weld. Then sanded the flange flat moving the pan on sheets of Emory paper.
The gasket-I like Milodon's but whatever you use, pay special attention to the holes in the gasket. Match them to the pan hole spacing then use a punch set to enlarge them (round) so there is no tension on the gasket when you drop bolts or studs in. I actually made a plywood jig so the gasket would lay dead flat with no interference from the bolts. Pay attention around the main cap drain as Brent says. I make a gasket 'sandwich' because of my windage tray.
Unlike Brent, I don't glue to the block-I glue to the pan, then the tray to that gasket, then the last gasket to the tray. I use the pan inverted an on the jig (which is flat on the bench) and weight it as the TA-31 dries.
It is tricky getting the pan+tray around the
oil pump, but there's no RTV to smear and can be done. I do this so that it's easier getting the pan off the block and I'd rather clean the pan rail on the bench, than the block rail upside-down under the car. I use a smear of TA-31 on the block so it can be sliced with a narrow putty knife for removal.
Finally, thanks to Jim Reiss, we had 'load spreaders' made from 3/8" steel and run front to back on both sides. They were water jet cut and the hole spacing is perfect to the gasket. When the pan goes on, using a bolt at each corner, I put one sides spreader in place and using Mr Gasket serrated head
longer bolts, work them up. Then the other side the same way. Torque with short box wrench until snug.
I have extensive pictures of all of this and will post only if you're considering doing all this.