My son had a '90; similar problem, though he was 5'11".
Going though a box of bar perches at my dealer I found a set for a old KX would fit; no idea which year but it did move the bars forward a fraction of an inch and up, and was for fat bars - nothin like my BRP RMX top for the '97 conventionals, but an improvement, nonetheless.
Call Thumper Racing in TX to see if they have Goliath Gear mounts for Suzuki - they move the bars way up and forward for bigger fellas like you.
If you have a buddy who will make an upper 3x clamp, that's good too, or if an RM clamp will work.