The soft-start feature won't be of any real benefit in the Paramour II, but you can still use it without harm.
The kit will work as-is on the Paramour II, but tweaking it a bit for more compliance couldn't hurt. I would change the 330K R2(A) to a 200K/3W resistor, and the two 149K resistors to 140K.
This will drop the regulated voltage down to ~283V instead of 300V, and rebias the first C4S for the lower voltage. In the Paramour, the string of Zener diodes won't be necessary.
I don't think the installation is all that difficult overall, but if you run into trouble, it will be difficult for us to support the modification since we have never performed it ourselves.
-PB