Should I go for LASIK if my number is -6.50 for both eyes and has a corneal thickness of 478 and 485?
These pachymetry (corneal thickness) measurements are somewhat outside of normal ranges. That does not necessarily rule out LASIK if other corneal measurements are all normal (e.g. symmetry). Some reputable ophthalmic surgeons would recommend an earlier version of LASIK called PRK in this situation, but I am skeptical that one is really safer than the other in such a situation.
You should consider other options as well. One is the ICL (Intraocular Collamer Lens) that can correct from -3 up to -16 diopters of myopia (nearsightedness) without touching the cornea. While ICls have their own risks, of course, these are unrelated to the degree of myopia being corrected, unlike LASIK.