Check this out and tell me the mag goes into the bulkhead but what should i do on the other side? make a U so it draws down? Just stick an extention so the pvd is in the middle? Or just leave it? here is a pic
It depends on HOW you are going to be using the sump. Are you adding baffles to stop microbubbles are you setting up a refugium ? Are you putting an in sump skimmer in it?
There are too many variables. But Like bad coffee said, you should use a true union on it so that you can detach the pump from the sump.
I suggest a either piece of spa flex or hose in between the bulkhead and pump, cuts down noises and vabration. A ball valve is a great idea, you don't have to drain the sump when you need to remove the pump.