Weld in a 1/4 by 1/8 pipe bushing
If you want the best use PTS pan
http://www.ptsnctb.com if you are low on money, have one welded or soldered in to your stock pan. I've tried the mechanical drains, always works loose, I've tried epoxy--ATF/heat always made the epoxy give up adhesion and now I wire weld the 1/4 by 1/8 pipe fittings in at the furtherest back corner.
Here's what I do: Drill a 3/8" hole at an angle but mostly horizonal, use a punch tap around the hole to drive the lower portion down so more oil will drain out and increase the size of the hole until the fitting will just screw in, then install a BRASS plug (wire weld will not stick to brass), and wire weld the inside and outside of the bushing to the pan. Grind down in/outside to clear components and look finished.
An alternative is to use acid core lead solder and a propane torch--acid core solder will stick to steel if it is clean. If you do not have access to both a wire welder and grinders this is the better choice.
Whichever you do take a close look at what's in the trannie that can interfer with the drain.
Never put a drain in that sticks straight down, I had a piece of road trash grab one out of my oil pan!!
I have an Art Carr aluminum oil pan setting on the self if anyone wants to make me an offer--its too deed for my very low car.
Hope that helps, if you have another question search the site--most questions have been answered many times.