If Reagan showed up today and had the same positions he did in the 80's, he'd be shredded in the republican primaries.
That is actually true, but if he had those same positions then he would have gotten shredded as well. The reality is that the public persona, the image he was selling to his base was vastly different than what was actually happening. What makes Reagan revered among most conservatives is not the policies, actions or legislation during his tenure, it was the renewed sense of confidence in America, putting the US back in a position of strength and to stop getting pushed around by idiots around the world who viewed us as soft. Often policies, actions and legislation were not at all in agreement with what conservatives would have wanted, but because they believed in Reagan they were still OK with it whatever was going on. Reagan also had to deal with a hostile democrat congress, but he unlike our current "leaders", he was able to work together with the other side to get things done rather than just whining about them not doing exactly what he wanted.