Give 30 mins of your time to the pan.
The bottom of the trans is machined nice and flat so the pan should be too. Thing is they get banged up. While it is off you can use a ball pien hammer to dimple the bolt holes outward, then lay the pan flange down on something flat for checking and correct bends or warp with whatever means nessesary.
Even a cork gasket will seal it without rtv and such when done right.