Have a 2000 IS with a Motorvation Formula II.... project.
Unless you are a pretty good fabricator/welder, it will be a LOT easier to purchase factory mounts. I re-installed a hack I had on my GL1200 - the Valk mounts were about $2k.

While pricey, factory mounts are good for piece of mind. There are tremendous forces exerted on the hardware when going down the road at 80 mph, or cornering, or hitting potholes at speed, or braking hard, etc.
Here's some pics.




And the (almost complete) result:

While not for everyone, Hack guys/girls are an especially fun and crazy group... The best fun you can have with your clothes on... The assimilation will be easier if you can turn wrenches...

. And get ready to add words like raked trees, fork extenders, steering dampers, heavy duty shocks, toe in, hack wheel lead, etc. to your vocabulary.
One tip: when doing your alignment, ensure you and the hack and the tug are all on level concrete...

Feel free to ask any questions, but only till next week; I'm going on a trip up the Cali coast and won't have email for a blessed week...

...