Ph 8

A Clematis fanatic once told me "Never move a Clematis"
but I have moved them with no trouble at all.
Important not to disturb the roots.
Cut them out in a ball of soil if possible, and replace
immediately in a prepared hole.

I googled this out of curiosity and there seem to be conflicting opinions about pH - worth having a look to get the broad view. If its a choice between taking them and leaving favourites behind I'd check first whether the new owners of yur house are gardeners and if they aren't very interestd then take the risk of moving what you can of the younger ones.and nothing lost if they don't make it.
Moving a mature one would probably kill it

I have pH 8.2 and grow several clems so don't worry. Just lift plenty of soil with the root ball so they are 'buffered' as they settle into their new homes.

You need lots of strong cardboard boxes, and lots of newspaper to screw up and pad round the root balls as they will shake about in the van.