What do you think the best power/drivability combo is?

I agree with Bobzilla. If the cost of building your own turbocharged ride isn’t to scary for your wallet, it is a home run IMO.

The great thing about a turbo is how easy it is on engine parts. In a over simplified way.
The engine is basically running down the Hwy. on zero boost and doing what it would do as a NA engine. So a small engine, like a 273, 318, can get 20-ish mpg and then get a boost from the turbo for power when you he demand comes in from you.

As always, a big roll in mileage and power come from the camshaft. Finding a cam that can deliver booth is the trick. Unless, there is no care in mileage. At 5/6 hundred ponies, I don’t think you car. LMAO!!!!

As I said earlier, it will take a lot less cam to do that power level. Bigger engine, smaller cam, moderate boost levels.

Are you pondering a turbo build and if so, at what displacement?