The post above yours suggests your quite WRONG about not being able to get the "sound"..... at least that's what his clip is telling my ears.
As for results?
Modern Tech is pretty tough to beat. Incredible MPG and Power is a Combination the old engines with Carburetors on top simply can't even come remotely close to in "stock, from back in the day trim". But I wouldn't be so quick to discount the potential of Updated tech in the older designs for making power.
In a TOY like the old Corvette I put up in the OP MPG isn't much of a consideration worth my effort in a car that sees so very little use each year. The 383 in it today benefits from things that weren't typical and available in anything but super high buck efforts in the 1960s and 70s.
A roller cam with faster ramp speed, computer designed and cut aluminum heads are at the top of the list of things that squeeze out big HP that would have been a lot tougher to find back in the day.
This car is a MILD use of what can be done today with old school tech and yet it'll run the 1/4 mile right along side my 392TA. It's Dyno proven 455HP at the crank is less than the 392 in the TA can make but it's a car that weighs in at just about 3,200pds after all the changes I've made over the years to it's suspension and under the hood so it gives up nothing to the TA in a straight line sprint.
For a look at what can be made of "old school" tech today, if you're willing to spend the money, without power adders like turbos, nitrous or super-charging..... read on and take a peak at the videos. In this MOPAR forum I could and probably should have highlighted a stroked, modern take on the 340 or 360 but since my old Corvette is a SBC so I'm sticking with the theme.
It's hard to call this car built by Nelson racing engines a SLEEPER but I think it just about qualifies and lifting the hood after a race to reveal the "Stock appearance of it's original 302" would be a real surprise for anyone who mistakenly believes it's the original 302. Modern motors have better stock vs stock flow vs. the old muscle motors for sure.......but a lot of the stuff that makes that possible is now being applied to older design starting points in the after market.
This car has a stroked 427 SBC and a carb and heads that flow very well, enough to supply enough flow to make the REALLY BIG power revealed in the video. I really doubt even a Hell Cat could take this car on and expect to win a 1/4 mile sprint. At barely over 3,000pds (that distinct lack of MODERN tech has a big advantage in the leaner weight figures).....650HP is more than enough potential to bury a 700HP car carrying more than a 1,000 extra pds. Though it's still absolutely true that the Hell Cat can achieve 2x and possible 3x the MPG on the ride home vs.old Camaro. God knows if I gotta drive it to work and around town every day I'm not picking the old car over a modern car.
Camaro DZ 302(NRE Stealth 427CI) Street Test. 1969. Nelson Racing Engines. Chevelle, Camaro - YouTube
For a more in dept look at the SBC 427 Nelson builds:
New 650 HP NA 427CI(7L) SBC from Nelson Racing Engines. NRE TV Episode 211. - YouTube