185/70/15 is available from Vredestein and Dunlop sport classic without the issue, that the car must be at least 30 years old. But I don‘t think, that the tyres are the main problem here, because the above information is trivial and MMC will know what the market offers. Perhaps it is the engine issue and the calculation how much must be invested to fit a new engine, regardless if a Ford turbo or a Mazda NA....Or they have a difficulty to get another engine at all.