500t vs 200t - 250D vs 50D

Hello everyone! I'm about to shoot a project in 16mm and I have some doubts about film stock. I'm not from the US and can only get 500T and 250D stocks. I've seen people say that 500t on 16mm looks extra grainy and it's best to shoot 200T. I've also seen people say 50D looks better than 250D. I could order the film stock from B&H or somewhere related but it would be 1. A lot more expensive and 2. A bit riskier. So my question is, are these claims that 500T looks grainier true? Would it be worth the extra money and hazard to get 200t and 50D? FYI I am planning of overexposing 2/3 to 1 stop, exposing the shadows, printing the highlights, etc. I will be able to test this (but due to budget and time I can only test what we're good to shoot with)