Hi,
Revaluation will adjust the value of the inbound item ledger entry and forward that new cost (zero) to the outbound item ledger entry (COGS) i.e. field Cost Amount (Actual). However, this will reverse out the total balance of inbound and outbound entries. The reversal of G/L will mirror the original G/L accounts.
I understood, you only want to reverse the COGS entries (negative item ledger entries) and not the original inbound stock take. In that case think you need to us directly G/L journal to 'correct' the original posting.
Think this is the only option available. Hope this helps. Let me know if I misunderstood the query.
Christiaan.