Well, i think im gonna go CA. Supposedly just swapping in an SR turbo and adding a boost controller can yeild 220-ish whp, assuming you went fm intercooler. This is from what ive read thi, so dont take my word for it.
And I guess it you gotta through on your own BOV and probs get an ecu tune before u do anymore upgrades after that.
But a CA swap should run you about $1300 plus intercooler cost, so it is a cheap way to go. And you don't even need that much hp in a drifter, right?
And as far as the mileage for the 383, just change the gearing. Look at a base model corvette. It has a 6.2 L I think, and it still gets 26 mpg highway. Just chance the gearing and jeep them RPMs wat dar down! Its not like you need shorter gearing with a 383's power output