Just because you can compile something for a platform doesn't mean you should

[classicdrogn]

In that kind of situation, it really sounds like you'd be better off writing your number cruncher for something like Tiny Core Linux, which at least already has a 64-bit version, rather than 'doze 3.11. Even more so if you can send it to a graphics card for the calculations, because while finding drivers for obscure Linux distros can be a challenge, I'd expect the solutions for 3.11 to start at "write one yourself," have a high chance of ending at "go back to running it on a modern OS."