If that soil tested 3.9 4 yrs. ago, it'd be quite surprizing if it is any more than 5 at the present time. It takes a bunch of lime to push it over that magic 7 number. As for that thin topsoil, plant some iron clay peas, or Austrian winter peas and work any fodder left in the spring, Till it in. Building up the topsoil will be your hardest chore.

Russ