By this logic, during the ACW, cotton plantations should start generating gold with cotton bonds
The "gameplay" switching from bimetallism to the gold standard should immediately make most silver mines unprofitable, evaporate a huge chunk of wealth, and constrict your economy, while staying with bimetallism for too long should lead to the global economy soaking up your gold and sticking you with all their soon-to-be-useless silver.
But again, I think the silver->gold recession is probably the least fun part of a gold standard to engage with. Liquidity, bank runs, and specie flows are a lot more interesting to interact with.
200mn is still a lot, that's nearly 10x Britain's starting GDP. The current gameplay has a much bigger private sector and much smaller public sector share of GDP.
Checking through the wiki, minting is 5.2% of GDP. That's a lot of money! Per Our World in Data, that would allow 1900 France to cover the entire cost of its military twice-over.