The way I've done it several times and will have to do again in the near future is by using (yes, this can be very dangerous so do so at your own risk if you choose to do so) 550 paracord. I believe the front springs are rated at about 210 lbs/in and the paracord I use is rated for somewhere between 200 and 300 pounds, sustained. After compressing the spring, I tied the cord to one of the top coils then ran it down and tied it to one of the last coils and, without cutting the paracord to start a new string, I ran it back up to one of the top coils, tied it and repeated this until there were about 10-15 runs all right along one another, not spaced out. Arrange it to where the tied down portion will be toward the inside of the car, facing the crossmember. It's a pain to undue once it's back in the car and being compressed by the control arm unless you choose to just cut it. Doing it that way though holds the spring in the position it would have if it were installed and makes it easier to install. If you opt to tediously remove and reuse the paracord be careful not to damage it while removing it and don't reuse it if it does get damaged, they're relatively inexpensive.
This also worked with the full length 275 lbs/in Mustang II springs that I installed in the front of my 86 GT, though I'd be lying if I said I wasn't more careful and sweating a little [a lot] more while handling it.
Edit: be sure you'll have access to the coil you tie the paracord to once it's installed so it doesn't get pinched and stuck.
[This message has been edited by hye_4_life (edited 09-11-2017).]