Yes a 4.7 or similar well built will crap all over a stock big block for everything other than towing bulldozera abyway. I remember at Yandina gymkana years ago there was a guy who turned up with a 4.2 Holden in a shorty Landcruiser, people laugh at the Holden 4.2, but by the end of the weekend comparing it to 454,, a 351, supercharged 350 chev, and Chev diesel V8's it was the sweetest sounding V8 there and an sung through the rev range from low quiet rumble to 7000-8000 rpm never missed a beat or failed in the mud an crap washing over the hood, while others had rough sounds missing and backfiring as soon as they got wet, and generally spent the weekend with their bonnets open.
I don't know how these 7 litre motors are going to get an engineering ticket without brake upgrades etc, as last I heard in QLD the biggest you could go with a petrol engine in any vehicle was about 20% over stock even with upgrades. Even it is legal, it sounds to me a lot like the same result you get dropping a 5 litre into a Hilux, a twisted chassis 6 months later. Cool, 800 horses you can't risk using regularly, I wouldn't say a JK chassis was exactly beefy
