I ride an '08 FLSTN and my H-D workshop manual states for '08 FLST ; FLSTN & FLSTC the forks take 13.4 fluid ounces or 395 cc's.
It also states to use these figures if the fork is left in the frame( not disassembled). Merely a drain and change---
It goes on to add:use 4.41 inches or 112.0 mm IF the fork is disassembled.
Meaning, that is the level from the top of the fork tube with the spring removed and the fork fully compressed: to the upper level of the fork oil in the tube.Once you've refilled it.
You can use whatever fork oil you choose.If you go too high a rating,your forks will be quite harsh and uncomfortable over bumps.The manual recommends( what else?) Harley type "E" fork oil #99884-80. Like I said,use Belray or Castrol or Harley or whatever.You'll know when you've gone too hard.Personally, unless I've pulled the forks off and stripped them, I just let them drain for some time and put the "left in the frame" ammounts back in.
I think the H-D type E equates to #10 weight fork oil. THINK only because I couldn't find my bottle of Type E.
Interestingly enough, I Googled 07 FLSTC fork oil capacities and came up with this:
"---FLSTC/N 2007→ 13.4 395 13.4 oz / 395 ml - Fluid level: both sides 4.41” or 112 mm ③ "
A direct quote from 'Tech Stuff' from "W & W" Cycles which substantiates the volumes listed in my '08 manual.Or that is a direct quote from The Book--
I checked my 2008 Parts and Accessories catalogue and it states that Chrome Lower Fork Sliders p/n #46482-07 fit '07 later FLSTC and FLSTN and '08 FLSTF's.
So I guess those capacities will work for your bike.