Is it common to make user interface elements (text, edit boxes, buttons, etc.) larger in an iPad app than in the corresponding iPhone app?  Would it violate any Apple UI guideline and get us rejected from the App Store?

I'm asking because we have an iPhone-only app now and some users really like using our iPhone app on an iPad Mini. They like the large text and large buttons when it's in "2x scaled" mode.

Our users are delivery drivers who primarily use the app for viewing the contents of delivery orders and doing numeric data entry in the field, so data entry efficiency is really important to them. We've even built a customized numeric keyboard to squeeze every possible bit of efficiency. 

Now we're designing an iPad-native app. We want to do this because we want to capture edge-to-edge screen real estate that we can't with the scaled iPhone app. Also, we get a lot of support calls from users who try to install our app on an iPad and can't find it in the app store because they need to filter their search to iPhone apps to see it!

As we design the iPad app, based on our user feedback that larger is better, I want to make our UI elements larger than the iPhone version. 

I don't think we need to blow everything up 2x, but instead I want to test various different scalings with users to see which size they like best. I suspect we'll end up with around 1.5x as the sweet spot between gaining efficiency via large UI elements and gaining efficiency by avoiding scrolling.  

Anyway, some questions: 

 - Are there good examples of iPad apps make good use of large-size interface elements to optimize data entry efficiency?  Ideally I'm looking for inspiration beyond calculators and phone dialers which are the obvious examples like this. 
 - Should we blow everything up, including the top-navigation bar? Or should we make the navigation the normal size to align with how most iPad apps look?  If we do decide to make the navigation bar larger than normal, what are examples of other apps which have done this effectively? 
 - Are there any documented (or not) restrictions by Apple for larger-than-normal UI element sizes for iPad apps?