Not enough. Let's put it this way. I use 1.12" torsion bars on my Duster. I have about 1" of clearance from frame to bump stop on my car. I occasionally still hit the bump stops. The wheel rate on my car is 300 lb/in with those torsion bars. With stock 318 bars, it's like 100 lb/in. So if you wanted to NEVER hit the bump stops, you'd need 3" of clearance. Now, that's not how the factory bump stops are used, so, you don't need that much. But, 5/8" is probably only 1/4 of the travel you need to have to the ride the factory intended with those bars.
You have should have enough adjustment to get back to the factory specs. But your ride height will be much higher. If you wanted to keep the ride height the same as it is now, you would need to change out a whole bunch of suspension parts.
