Worthwhile to change the old compressor?

New compressors work more efficiently, but not more effectively. Replacing the RV2 with a Sanden shorty would save a lot of weight, plus off the front end where most helpful. You can find bracket kits for your SB engine (Bouchillon I recall). You probably need custom hoses to connect, and I think you can lose the surge tank on the suction side.

Study your options for refrigerant. R-134A is now "bad" and to be replaced soon. I have used Duracool, but mention of HC mixtures raises some people's ire.