Woohoo, I used Robopottamus and GCExcel's suggestions as a jumping-off point and got it to work! Here's the formula in case others might benefit from it:
=IF(AND(C4="D01",I4<50),I4,IF(AND(C4="D08",I4<50),I4,IF(AND(C4="D01",I4>=50),50,IF(AND(C4="D08",I4>=50),50,""))))
I was...