I also found out from my local husky dealer that ARC makes shorty style adjustable reach brake and clutch levers for the SMR 450 and 510. Here's a link to ARC's website: http://arclevers.com/index.php?route=common/home
I believe the brake lever is part number BR-103, the long style clutch lever is CL-103 and the shorty style clutch lever is CL-105. The levers come in either aluminum or composite (memory plastic) and have a lifetime guarantee so the website says.
For those with questions about chain adjustment on the 450/510... this sticker was on the swingarm of my 2010 SMR510. To me anyway, it reads that you put tension on the chain to make the lower section of the chain fully taut. Then, you take your measurement 145mm from the swingarm pivot axis. At 145mm from the swingarm pivot axis, the upper chain section should have 30mm of up-down movement.