eff your in luck and this job is a piece of cake.
You lucked out by finding the solder nipple (the hex fitting)
Simple task just pay attention FORGET the 18″ wrench its useless and the liquid wrench give to a helper to sniff in a corner as it wont do a darn thing here
1- Get any saw and cut off the excessive length of lead pipe so you are now working like a gentleman
2- cut about 1/2-3/4 inch from this ell bow.
This solder nipple is brass so its soft metal and very easy to cut.
3- Now take either a hack saw blade with duct tape on one end Or get a reciprocating saw (like a sawzall)
NOW Here is what separates the mechanics from the apprentices SKILL in following directions.
GENTLY saw this nipple inside wall GENTLY and slowly take your time this is not a race OK?
Your blade should be cutting the internal wall of this brass nipple as soon as you think your getting close to the threads of the ell bow STOP
Now move the blade either to the right or left of this 1st cut and do the same thing about 1″ AWAY SLOWLY again as soon as you are close to the threads of the ell bow STOP.
Take either an old screw driver Or a chisel and gently using ball peen hammer knock out this small cut section out.
Now with this piece cut out you can CAVE IN the open ends towards the inside of this brass nipple If you did it correctly you can just about unscrew this solder nipple by hand.
Now get a 11/2 Galvanized plug with rector seal # 5 or Teflon tape or paste and screw in this plug. Congratulations you are now officially as qualified as any 5th year apprentice LOL Welcome to the club.
Now considering you just saved yourself over $85 why not take this savings and make a small donation to the American Cancer society or St Jude childrens hospital. Thank you
PS if you REALLY want to get away FAST cut the threads BEHIND the ell bow and buy an 11/2″ No hub cap if you have the room and just cap the pipe, BUT this takes all the enjoyment out of jobbing plumbing.