4.3l v8

Does anyone on here know much about these engines? I know that there were 2 different 5.7 Blocks, D and the later DX. But, I wanted some more insight from someone who may have worked on one. I saw a Cutlass G-Body supreme with one before but never thought much about it. I only got into GM...

Hello folks how’s it going, I just got a deal on a 78 cutlass supreme brougham the engine has a rod knock I was hoping to get some info on rather to rebuild the v8 4.3L 260 motor or swap it out with maybe a Chevy 350 block OR WHAT OTHER MOTORS ARE CAPABLE FOR THE JOB if so what all would I need...