68 Barracuda Fastback Rear Shock to Gas Tank Clearance Question.

Hello. Finally picked up a 68 Fastback to work on. I've done lots of restos on B and E's. With those cars I have been able to use the spring over shock method to raise the stance of the rear. On this Barracuda, I can barely stick a finger between the rear shock and the gas tank so no room for the lift springs. Car has an 8 3/4 rear. Are shackles my only option here to raise the rear. Car still has it's 14 inch wheels and I plan to go to 15 inch Cragars with 275 tires so I want to get the rear in the air and crank the torsion bars up. Any insight would be greatly appreciated. Thanks.