As much as I would love a 408, I would be looking for a similar LA360. Highly doubt my 904 trans, rear end and suspension could handle a 408. Unless I am wrong....
There's other builders that offer crates, Blueprint does offer a milder 375 hp 408, even if you do somewhat mild hop ups to 360 you'll be around there. What is your rear end ? if 7 1/2 not strong enough any V8.