I don't have a Form 8990 in a personal 1040 return to report the excess taxable income from a K-1 (1065), line 20, Code AE.  Does this amount go on Line 21 of a 1040

Well you need to get a Form 8990, then.

"It's a partnership pass-through informational item, not additional income at the 1040 level."

Unless there's some addiotnal kind of information telling what type of excess taxable income it is, I guess Line 21, Other Income is the winner.

This is in refernece to the 163(j) business interest limitation and Form 8990. Is there excess business interest and Adjusted taxable income on that K-1, too?

no