I have a mobile version and a standard version of my website. I'd like to show users some pages on the non-mobile site but keep googlebot mobile out. Is that ok?

[bgs]

On the mobile version not all the content of the normal site is available to the users. Since we didn't want googlebot mobile to index the non-mobile site, all the non-existent pages were returned with a 404 error.  But now we'd like to show the mobile users these pages and send them to the normal site. If we allow the users to see these pages, is it ok to block googlebot mobile so these non-mobile pages are not indexed by googlebot mobile or will that create some issues for google?

[AxialDev]

You're on the right track as far as showing users the PC versions of pages without an equivalent instead of the 404's: "If your content is not available in a smartphone-friendly format, serve the desktop page instead." -http://googlewebmastercentral.blogspot.ca/2013/06/changes-in-rankings-of-smartphone_11.html

However, you should let Googlebot (mobile or not) crawl your site the same way as your users would, which means you shouldn't block googlebot-mobile. It is totally fine for a desktop page to be ranked in the mobile index. It's not ideal (see article above) but it's better than not being there at all.

Think about it this way: if you're OK with your mobile users to see non-mobile-optimised pages, then it doesn't matter whether they come from Google or not. The page is still relevent to them.

As an extra, you could consider making some of the non-optimised pages responsive such as to make the user experience a bit better. Sometimes a few tweaks here and there can make a difference.