Yup ot's only $$$$$$$$$$$$$$$$$$$$$
Heres a big block for ya,, on EACH SIDE,, 904 cu in. This ones in the 3000+HP range in a D bar D's nitrous Promod but point is,,, you can make just about anything these days if you have the $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
BR3 is the man,, Turbo LS is where I'd go too. My son is building 58 COE with a 415 C. In. LSx with a single 85mm turbo. Motor plan should have it around 650-700 on pump gas with streetable boost, and tickle 1000 with C-14. He's $12k into this motor in parts and pieces and it's not anywhere close to final assembly / plumbing / wireing if the motor yet.