i wouldn't recommend fastening them to the spring. there's a chance you could bottom out and somehow crush the brake line, or bind it up, and them you'd have no brakes, and it probably won't reach anyway. there should be a space about an inch tall b/t the bottom of the threads on the strut body and the fork (the wishbone shaped bracket). just zip tie them in that area. i have a picture from when my hub nut sheared off that has the zip tied brake lines shown if you need it.

my springs were about the same size, too. you said there was painted lettering on the springs, right? the spring rate is probably part of that number. if you can, post the numbers, and i can probably tell from them. if the lettering is not part numbers, then the thicker spring should be the stiffer one, and that's your front. just to be sure, grab a couple coils on the different springs and squeeze them. whichever is harder to move is your front.