I am a Surveyor but these comments are non-Surveyor type comments:
I don't know exactly where you are but the general neighborhood plan looks like the intention is to have expansive front lawns with all the houses back from the street a large distance like Arden Park here in Sacramento.
If I was your neighbor I would object to you building your house sticking out from everyone else 15' out of character with the neighborhood.
Typically in California platted setbacks hold despite the current zoning. Which ever is the larger distance holds.
I have seen a few plat amendments around here (Bellevue, WA) that have dealt with this issue.
I will typically locate the face of adjoining houses, when doing a survey for design. If all of the other houses are back 50', and yours is back 35', that might make someone call an attorney. (At least around here.)