Johnny Herbert and Alessandro Nannini are two of four new drivers that will compete in Grand Prix Masters, this week's Autosport reports.
The pair of Grand Prix winners will be joined by Roberto Moreno and Raul Boesel in a revised series, with four races likely to take place this year.
The cars will be powered by 4-litre Mecachrome engines, replacing the decade-old and revised IRL Cosworth units that were supplied to the series by Nicholson McLaren. The series will also switch from Avon to Michelin tyres.
Existing GPM drivers were involved in both deals, as Eddie Cheever secured the engine deal and Rene Arnoux helped put the Michelin agreement together.
GPM operations director Bob Berridge said: "We are delighted with our latest recruitments of drivers and suppliers.
"It's all a manifestation of a series that is now moving into an established position after all the normal start-up fire-fighting and cavalry charges, and we are now ready to really begin to exploit the potential of the Grand Prix Masters concept."
The series will race around the streets of Bucharest in May, when the FIA GT and British F3 championships will also be in attendance, and it will return to the scene of its successful opening race at Kyalami in September.
There will be a race at Qatar's Losail circuit on a date still to be confirmed, and at a fourth venue which is promised to be a 'big surprise'.