Hi Drew,
If you're looking for a aluminum FE block they are really well made and very reliable. I'm not sure if you make only 400 hp with a FE combo. I've built a few Shelby 482 engines. The ONE BIG note is to build a roller cam engine. Todays flat tappet cams can fail so easy and that can cost thousands to fix.
If you're serious about building a Shelby 482 combo, I have everything in stock and an engine machine shop & dyno to test before shipping.