8" is insufficient to begin with and if supporting a timberframe with a block foundation you would normally insert rerod through the cores and pour them solid under each post location.

If I were in your situation I would design the frame to be smaller than the floorframe by the thickness of your chosen enclosure this would provide a ledger for your enclosure system but more importantly by pushing the frame in part inboard of the blocks this would allow you to support it on pilasters retrofited into place.

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