There's no point in reviving any old car brand if it's gonna be the same modern hyper computerized, cost cut at any expense, plastic interior, turbocharged high-revving unreliable engine with a rubber oil pump belt, VVT, EGR, electric thermostat and water pump, more wiring harness than engine, impossible to repair, oil burning low tension ring, cylinder deactivation camshaft-eating, electric emergency brake, electric power steering and brakes, cloud-connected microtransaction location-tracking cell internet gps, no buttons, giant touchscreen BULLSHIT that they make every new car like, be it a SUV, crossover, sports car, pickup, whatever.
To REALLY revive the SPIRIT of what the old brands were, you'd have to make them COMPUTERLESS (or at least use 80s computer technology that is simple to repair), MINIMAL plastic use, most of the interior made from real metal or wood, engine from real steel and aluminum, reuse old time-proven and aftermarket supported engine designs that have ALL parts available aftermarket (DON'T invent some new part only for this model that will be unobtainable after 10 years and will total the entire car)
Basically remake old car designs, like faithful clones or reissues, don't shit them up with modern garbage. It should have the bones of a simple, reliable vintage car, not just lipstick on a pig (a modern unreliable shitbox made to look like a vintage design just to lure customers)
Since modern road safety and industry overregulation laws make manufacturing stuff like this ILLEGAL, (stuff like active driving assists, ADAS, emissions...) you would first have to REPEAL all NONSENSIAL government regulations that prevent such a car from being manufactured. Only then could you make a SIMPLE, RELIABLE, ROBUST, GOOD LOOKING, MAINTAINABLE CAR again.