The 440-
4221 13" are HD springs.... as recommended for all ISs.
I'm 180-5, lightly loaded

and always solo on my IS, and mine have never been off the lightest preload setting. And they aren't
cushy.
I'd try them at the lightest setting first.... and am guessing that if you need more, two full turns would do it for you.
Mine have always been a bear to turn (I have two bikes, with standard rate 440s on the other). Pull the bags*, and I think it's easier with the bike jacked up just enough to have the tire barely touching (not hanging in the air either). Strap wrench was a PITA resetting over and over, I wore rubber gloves for grip. I have never been able to clearly see/count the tiny threads poking out the top, so I put a small nick in the chrome at the lowest setting facing straight out, and count full turns from the lowest setting and write it down in your shop manual or maintenance book.
*the bags have to be pulled for install anyway, leave them off and go for a short spin, intentionally hitting bumps, dips, manhole covers, RR tracks, yada. (Throw the bag weight in the trunk). Spray a little WD or penetrant up inside the top covers.
And, while a longshot, I'd go back to your Evilbay seller and ask if he has the sales receipt for the 440s. If he does, you suddenly got a lifetime warranty (this may not be strictly on the up and up, but PS does not look beyond the receipt itself).