I found these items while cleaning up the parts shelf in my garage. Since I no longer have a SuperHawk, I don't have any use for these.
1.) Aluminum Axle Spools - these are the same one the have been selling on eBay for some time. I never used them since I have a stand with a flippable head for spools or a frame. They fit the CBR600 F4/F4i and VTR1000 for sure, and I'm not sure what else they might fit. One has a smaller shaft than the other, but the guy on eBay actually has pictures of a bike up on a rear stand with these. $15 shipped
2.) Hudson Valley Motorsports Heavyweight bar ends - these really took the vibes out of my clip-ons. They are the extended version, weighing in at 13.5 ounces. These will only fit a Honda. $40 shipped.
They require the internal hardware (the threaded insert that is in Honda clip-ons/bars) to work. I have no idea what the end of a Renthal looks like, so I can't accurately answer your question, but based on the Renthal website, I'd have to say 'No'.