how can i replace my mechanical gauges into electrical?

i know of no way this can be done

Are you inquiring about how to replace the mechanical gauges with lights (ie. "idiot lights") or to replace them with an electronic dash cluster? If you want to replace them with lights, you simply need the proper gauge cluster from a lower-optioned vehicle than yours. If you want to replace them with an electronic, more modern dash cluster, this isn't really possible.

what if i want to replace mechanical with electrical?

hoe can i pull the stripped bolt off the valve cover?

like said cant be done.what you want to do,as far as the stripped bolt are you talking head of bolt or threads from v.c.to head.