Aah that's where we differ then, I think this car being rare should have it's engine. As I've said before a rare E Type wouldn't have a modern Jag engine installed. Also the Don Muscles car IMO has been improved a great deal from what it was hence the cheering. This car has gone the other way (but is a great car) - these things are personal choice.
Also why that engine in a car with limited roadholding etc. ?
'Rare' doesn't necessarily mean desirable of course. 2/2 models are relatively rare in Japan because they were less treasured than the two seater models, so they have a lower survival rate. Personally I wouldn't choose one over a two seater.
The car in question has fully reversible modifications as far as I could tell. I doubt it will happen, but if somebody wanted to put back the original L20E drivetrain they probably could with little difficulty.
Why that engine? Well, it was hooked up to a modern automatic transmission. It's a cruiser! I bet it wafts around very nicely and for that type of driving the RB25DE Neo is a good choice. Whole engine and trans could probably be bought for peanuts in Japan, and probably cheaper than rebuilding an L20E. The wheels and hubcaps were probably only on for the show (I might not have snapped the first picture if it was sitting on this week's 'cool' wheels...) and I see wheels and tyres as a moveable feast anyway. Like shoes and socks, I always have a few to choose from.
For me there's simply no comparison between this car and the Don Muscles car. Referencing what the DM car used to look like is all very well, but I don't personally believe it has been 'saved'. More like a stay of execution if anything. The red car has had a body restoration and repaint to pretty much ex-factory stock condition, clearly with lots of rare OEM parts hunted down and rounded up at some cost. No 'personalisation' body and paint-wise. It's almost bone stock.
Two quite different situations and with quite different results.