We stock the 418 boost setups. Honestly the 427 using a LS3 block is a bad idea for boost. Give us a call & we can discuss options! We have 427s for boost, but it wont use the 6.2l ls3 block. I've personally made over 1000rwhp with a 4" stroke setup like the 418!
We can help you build a nice short-block that will make the power your looking to make.
Typically we keep around 40 short-blocks in stock at any one time. If we don't have exactly what your looking for we can build it in under 3 weeks!!