I have a '67 GTO 400, automatic with everything mostly original except the carb, transmission and paint. If I were to sell this car today, what would I list it for?  

IMHO fishing on a forum and/or using auction results will not yield a true value. At the end of the day it's only worth what someone is willing to pay. With that said researching online can get you in the ball park. But if you really want to know get it appraised and work from there. Case and point this 1967 is a true 242, with OE engine, trans, rear and interior. It is however in none original color. It was a full frame restoration about 20 years ago. It was originally a 2bbl cruiser that we have built up to emulate an HO, It's still a cruiser but just looks better  It appraised a year ago for $52 but we know real world value would be $45 and we would take no less than $42.  

SPRINT6 is correct. Getting someone to accurately appraise the the value of your car is the best approach. 

That said, the attached link from Hagerty collector car insurancegive you a ballpark of values.

https://www.hagerty.com/apps/valuationtools/1967-pontiac-gto

I would hazard to guess that your car falls into the "Good" category without seeing any pictures. What hurts you is the lack of the original transmission and carb. That will detract someone looking for a numbers matching GTO or a concurs level. The re-paint may or may not hurt the value based on the quality of the paint job and how well its been maintained. This is, of course, my opinion.

Your GTO is worth keeping, thats what its worth!

What I also forgot to mention is 1967 is one of if not the hardest year to sell. Pontiac sold lots of base '67's unless you have something unique it just becomes lost in the crowd. It took me over a year to sell the Hardtop, albeit was a very personal built street/strip GTO. I was looking for 30 and agreed to 25.9 in the end, as it went to a very good home.