As much as I'd like to help you spend your money, I think you should use what you have and try and get some more out of it. I know its been a few years since you've run the green beast but I remember thinking it has more in it with more tuning.

There's no reason you shouldn't be able to go bottom 10's or even high 9's with an Indy headed 408.

If you're set on making the switch, you should buy Ray's short block.