Unfazed, Tweedie put in a brief sprint, opening up a gap on the field, before rolling it back and cruising to the line with Ross - who had restarted in seventh after putting a wheel off the road in the lap one fracas - the big mover after snatching second with just over a lap to go, ahead of Zazryn, with Proctor, who had slowed significantly on the last lap, fourth.
Fifth, meanwhile, was former MSC series champion Ian Clements (Lola T332) ahead of a superb debut performance from Melbournian Peter Brennan, in the beautifully restored ex-Lella Lombardi Lola T330.
Bryan Sala was another to fade for seventh, from Bill Hemming (Elfin MR8) and David Arrowsmith (Lotus 70B), with Mike Glynn's Elfin MR8 completing the top ten.
Sunday saw two more races, a qualifying heat in the morning and feature in the afternoon.
The feature proved another Tweedie benefit, but the morning heat eventually went to 2013 MSC series champion Steve Ross.
The Dunedin driver got the jump on Tweedie at the start with much of the rest of the race run behind the Safety Car following a spectacular opening lap crash, at the end of Sandown's long back straight, which saw the Lola T332 of top local driver Paul Zazryn spin and hit the outside safety barriers - fortunately rear first.
While the car was heavily damaged, Zazryn was unhurt.
The heat was restarted with just two laps to go and, in a close finish, Ross was able to keep the pressing Tweedie at bay.
MSC NZ F5000 Tasman Cup Revival Series Historic Sandown round winner Tom Tweedie leading the field on Saturday
Fortunately the main event was virtually incident-free, with Tweedie getting the jump, racing to an early margin, and coming home some 15 seconds clear of a race-long battle for second, resolved on the last lap between kiwis Proctor and Ross in that order.
The talking point of the race, though, was the charge, from seventh on the opening lap to fourth, by former Formula 5000 great Alfredo Costanzo (McLaren M10B).
Having missed Saturday's race after blowing an engine on Friday, the three-time former Australia Drivers' Champion started at the back in the shortened morning heat, finished tenth, then in the main event worked his way one-by-one past the midfield cars, to finish a strong fourth.
Behind him at the finish were Dave Arrowsmith (Lotus 70B), Ian Clements (Lola T332), and Peter Brennan (Lola T330), while further back, the top ten was completed by a delayed Russell Greer (Lola T332), Bill Hemming (Elfin MR8) and Philip Lewis (Matich A50).