Newbie struggling with choices

Hey everyone, Jeroen here.

Rather new to the stage. Not even a van owner yet and already struggling. Hoping on getting some tips on things that I overlooked.

Here’s the thing: Me and my wife have three kids and a dog. And now we’re on the market for a van to build our own home on wheels. But the van is supposed to be for small (weekend) trips with the family and larger odyssees for myself or my wife and me.
The choice we’re struggling with is between two vans. 1: a mercedes benz 409 from 1977 and 2: a UAZ Bukhanka from 1980. The struggle is the size. We need to sleep 5, with a rooftop tent that is not a problem. But what’s your experience with living in the van. We have this romantic notion that van-life takes place around the van rather than inside. But before we spend our hard earned cash we thought it to be smart to ask around.
Thanks in advance!