you need to leave in 15A and B. these are adjustments for alternative minimum tax purposed 15A flows to 6251 line 2l. 15B can be either 1231 or 1250, or even some of each but it doesn't matter which you use.
from k-1 instructions for 15B
Code B. Adjusted gain or loss. This amount is your share of the corporation's adjusted gain or loss. If you are an individual shareholder, report this amount on Form 6251, line 2k. for various reasons the amount you enter for 15B and what appears on 2k may be different. there is a 6251 worksheet where 2k is calculated.
