i am a lefty and am wanting to build my own ar. while building the lower can i simply put the safety selector switch in on the right side rather that the usual left side?

no the detent holes will not line up

just get an ambidextrous selector.  they about 25 bucks

i shoot left handed too and i found 2 choices. ambi or a lefty i like the ambi cause my friends can still shoot my gun

another option, IF YOU'RE UP TO IT,(after all its the build it yourself forum) is to duplicate the stepped hole in the lower for the detent, on the other side of the  grip tang. this will put the detent on the other side. drawback is the positions are reversed. i.e.safe is forward.
rumor has it a new colt (dont know which one) can be reversed. dont know for sure. if it had the detents milled on both sides of the selector,from the factory, just for this purpose, thats obviously the way to go. i think its the one with a star looking thing on the selector lever.

I wouldn't mess with the safety at all, it could be dangerous to confuse someone by installing it on the other side with detents drilled into it.

Just get an ambi safety and be done with it.

I ditched my ambi safeties.  Just use your trigger finger or your thumb around the back of the pistol grip.