125# or 150# rear c/o springs?

Got the ladder bar setup in and now have to figure what coilover spring to "try" first? Getting the Jegs double adjustable ones and need to see if anybody is running them in a big block dart? 10 gallon cell in the trunk, battery relocated - be putting in a 6 or 8 point rollbar setup..... No scales or idea of overall weight. I know there's a lot to factor but a good guess would work for now, I can change later if necessary. They're on sale & trying to save a buck.....or more! Thanks guys!