It won't benefit from it, at heart the SF2 series is a monolithic game, the latest patches do offload some minor tasks to other cores but at least 90% of the work is still done on only one.
You would benefit more from having the best single-core performance you can afford.
Keep in mind that many modern CPU get increased performances through optimised path and instructions that would not benefit to SF2 because it never was compiled for it and relies on API versions that do not benefit from them either.
Considering the same principle applies to GPU, you might end up in a situation where older, "slower" hardware might get you better results than newer, faster one (or require high-end parts to see significant improvements over what was middle of the road hardware).
If you look at benchmarks, compare DirectX9 (eg. 3DMark 06) or DirectX10 (eg. 3DMark Vantage) ones, anything above that is not an indicator of how useful it will be to SF2.
Here are all the air units in the original SF1 campaign, only 436TFS used the F-104G from 1959 to 1965, using the F-100D previously and the F-4C afterward.
