LS engines are getting overdone, because they are easy HP.. SBC's still get done because everybody knows them and has at least a spare part or more..

So, take the easy out of it... I'd build a 250 I6 with a turbocharger. You'll get some decent numbers out of it. The 250's did come in Camaro's and it would catch everyone's eye

If you wanted to piss people off, you could use a Toyota 1JZ twin turbo engine which are dirt cheap right now. Course it won't sound quite right