Air shocks are hard on the shock mounts which are not made to take the extra load. Replacing a damaged shock cross member is very invasive and costly. It is really good to avoid air shocks.

I think choices you have are 1) Re-arch current springs 2) add a full leaf to current springs for ~ + 1" 3) combination of 1 and 2 4) New springs with desired lift.

Adding a leaf will increase both spring rate and height... kinda like air shocks. May or may not be good for your situation. Adding a leaf to my sagged MP XHD springs at a local shop cost ~$100 which I thought was reasonable... plus I wanted the higher rate.

I'd suggest you talk to a spring shop or two nearby and get their recommendation and plan accordingly.