This is a project car i bought not too long ago, i went to a mechanic and he told me its either a Head gasket leak or a some sort of value leak if anyone is 100% sure or just knows what they are talking about, can you please give me some direction on what to do or what needs to be done i just need help, its also old oil build up at the bottom near the oil pan/ on the oil pan i don't know if that can help with anything i'm just noting every problem that could possibly coordinated with the main problem

P.S the leak is right below the alternator