OOMod, LH autos in 20 ga. are very scare as are Benelli O/U's :wink:
Many of lefties shoot so called right handed auto's with NO problem. Most all of the newer Auto's come with shims and spacers to adjust the cast & drop for a lefty. I would also encourage you to consider a 12 ga. in lieu of the 20 ga.
Most 12 ga. guns will weigh a LITTLE more than the typcial 20 ga. and this will help with recoil. One can easily find 1 oz. 12 ga. shotshells in the 1100 to 1150 fps range that are very pleasant to shoot and in alot of cases more pleasant than they typical 20ga.
Good Luck,
RTA48