Actually redoing the barrels is not a deal breaker as far as value. It would be if the whole gun was refurbished, but 20 ga. 4E's are very rare and in good condition would bring a premium even with the re-blued barrels.
There were only 455 Grade 4's made and only 15 made in 20 ga., might be less with the HOT and ejectors.
All guns from Grade 4 up had the gold bar.

Blue Book of Gun Values, 70% condition, being a 20 ga. with HOT and ejectors is around $12,000 to give you an idea.

David