largely on engine displacement I think that some modern performance cars in street trim might have a chance given how far engine and braking technology have evolved.

Would I want to be in such a race with a modern performance car that I owned? Probably not. I'd be too concerned about my safety and the safety of my car. The only actual racing I've done was some autocrossing in the 70s so I'd likely be at a disadvantage against even amateur road racers. I would however enjoy driving the route that some of those races used like the Targa and the Mille Miglia.

Regarding Goodwood, I used to buy their Revival DVDs every year until they discontinued them in favor of streaming the races on Youtube. Back then drivers like Moss, Surtees and Phil Hill were among the field. They were old but could still race well. Your post reminds me that I should watch them again for priceless scenes like Surtees tearing around the circuit in a Ferrari 250LM.