Both will do; in the first case the continuation itself is rather what is meant , in the second what is meant is the drive of whoever is involved in the project to go on with it. These two alternative ways in the end amount to well-wishing for both the project and the succes of those involved in it in making it progress, as the two are inseparable.

They are both correct and similar, as you can see on this ngram:

They are constantly fighting even if it seems that “bonne continuation de X” is older and still more common to use.