Depends on the car, the driver and the circuit. Last time I saw one was at Castle Combe. Did quite well but was taken to the cleaners by an old Elan and came second.
Had a long chat with the driver in the paddock - interesting fellow who had been racing the car for years. Morgans are good cars for racing with light weight. Suspension is much less of an issue on a smooth flat race track and grip is mostly down to the tyres
Unless he's running ground-effect, I suspect grip is wholly down to the tyres!
(yes, I do know what you mean - when there's less sprung weight to control and fewer surface undulations, even a Morgan chassis can cope, and performance comes down to tyres)