a) "heavy duty rims" Heavy duty rims are usually heavier, but not 100% for sure.
b) "lighter than stock" How heavy is stock?
c) "i will get down to 240 but am currently 270" You can minimize need for a) and get by with existing rims if you work on c). I've got a secret that works.
"Any suggestions on an upgrade?" Put max effort into c) it's the healtiest choice

Else need more info such as what rims you have, how heavy are they, why do you think you need heavier duty, when will you be down to 190,