Troubleshooting gas tank install 1975 scamp

Over the weekend I cut out my rusted out truck pan as where the gas tank strap mounts were rusted out in the spare tire well. Got the new pan welded in wich was its own ordeal but we got her done. The final issue came when we whent to reinstall the gas tank. The back of the gas tank was hitting/ rubbing the rear shocks. Besides bashing in the spare tire well does any one have any suggestions on what could be the issue and/or what would be the best solution? Any and all help is greatly appreciated. Thank yall.