I have some Apollo Stepless Steel R/S shafts. The trim instructions for a 7 iron are trim 2" for regular and 3" for stiff. My question is... if I trim only 1" (for 7 iron) will this give my a Senior flex? I am only building 6 iron to AW so it would not be a problem to trim them all 1" less.

Seems reasonable.

Remember that you tip trim shafts for trajectory control, the greater launch you want the less you tip.