390 vs 408

Hi!

I'm having troubles deciding wheter to build a 408 or a 390 I will bring some thoughts and hope you can help me choose!

Pros and cons for the 390

+ Already have the 318
- Less cui

Pros and cons for the 408

+ More cui
- Engine will cost me approx 600USD (I live in Sweden)
+ Cheaper pistons

Other important things to have in mind

I want to keep as mild gears and stall converters as possible

It's a daily driver

A 727 will be parked behind together with a 8.75

It will be driven hard

Fuel economy isn't a top priority but it will be driven a MINIMUM of 60kilometers per day so the more mpg the better. And above all, reliability!

It's a '66 Dodge Dart

Questions

How much power difference will those 18cui make?

Will the 600 USD it'll cost to buy the 360 even the cost out? Or will one or the other be cheaper/more expensive? Oh and the goal is approx 500 horse at the crank

Any good suggestions on parts? I'm 18 and no millionare so it's in a budget but I'm here to teach those plastic and turbo-loving guys and gals that nothing beats cubic inch!

Is the 500hp@crank possible while maintaining idle and mild gears?

I'd rather have torque than horses, what will make those ftlbs show themselves?


Anyway! Best regards! You guys at FABO are the best!