By some standards Reagan was no conservative either. Trump’s two policy books and his support of Reagan in the 80s and his over all political pragmatism still shows tow things: 1) his principles are overall conservative and 2) he will be better than any den or GOPe
There is a difference between being conservative and being better than a Democrat and being better than GOPe. This isn’t a jab at Trump - I support him over anyone else - more of “expectation setting”. He’s not going to follow every Conservative position. If anyone expects him to toe every Conservative position they are going to be disappointed.
That said, I think he’s the best man for the job.
One lesson learned from the implosion of Scott Walker: if you don't have lots of your own money, you will need to depend on big-money donors in your initial campaign, and you will have to have your positions reflect their demands. Currently the big money Repub donors want immigration.
Walker's campaign died among conservatives when he started making pro-amnesty noises.