I know guys who have used the adapter plate with the GM case deal for years, like it, it works and they won't change. I used a JW bell and flywheel kit with stock GM cases behind a small block and it worked OK. Wasn't a big fan of using the pump bolts, but that's how they did it. If I were to start from scratch today, I believe I would go with the ATI case and bellhousing deal. ATL is a good company, I like their stuff, they support the sport, they've always taken care of me, and they are reasonably close to me. The JW/stock case deal may be a bit cheaper, but weaker. And the case would still need a shield. A plate system with a one piece SFI GM case would be second choice. I assume someone does them for SBM.