I think just taking the section 1 science would probably give us labs the same size as the Endeavor, so if you squint it could reach that mark.I seriously don't think it's going to have the Science score to be a mainline explorer without the big Scientific Facilities. The standard (small) Science Lab surely isn't going to be enough on its own.
It's just that with those size labs and the saucer sensors the Endeavor only reaches Science A relative for a sub-million ton vessel, which the Sovereign certainly isn't going to be seeing as it's already bigger than the almost 4 million ton Ambassador. So without those major science labs it's probably never going to be put on a dedicated science mission, regardless of how much range it has, because it's just not cost effective to deploy something so massive for so little relative return when they could just use a smaller ship with similar facilities.