I'm sorry I can't help you with the SP1 part number on an Inspire. Possibly check with both Oregon Motor Coach, Country Coach, or perhaps Kevin Waite will know the part number.
Also, suggest you call Koni back and ask to speak with Justin. I read that Koni had a more robust shock then even the SP3 that was being used on Alpine coaches. If they are coming out with a more robust shock, and confirm it would be available for the CC's - this may be worth the wait. (And of course if not, the SP3 is better then the SP1's - as you know.)
And yes, I do have Road Kings all around... I do think that most CC's would do well with Koni's on the rear, and Road Kings on the front. And I'm a fan of the Super Steer Motion Control Units (And Source Engineering also have a 'check valve' available now too.) They really do help these heavy coaches 'set' faster in changing side to side driving conditions, like mountah S curves. And provides a safety edge during emergency maneuvers. Not all that expensive either!)
And if you do talk with Justin and confirm that a new more robust shock is being made, or will be made, it would be great to share the info...
Best of luck to you,
Roo II is our 04 Country Coach Allure 40'
OnDRoad for The JRNY! Enjoy life...