Is it possible to get bore measurements on these two guns? We would be very interested in anything you can get. Bore diameters, chamber lengths, choke constriction, weight, barrel length, etc.

I'd recommend the Paradox if you want to actually use it as a slug gun. H&H even has Paradox ammunition loaded that may work in the gun you are considering. Holland should test it if they are doing the restocking job. As a last resort, it can be reregulated to the current ammunition. I highly recommend you load for it. Slight variations in original loadings limit the usefulness of the current factory stuff - It is not a one-size-fits-all situation. There are people here in the US that can do the load workup if you like.

The explora required a special projectile to work as origianlly advertised. Unfortunately, the slugs are not available. I have seen targets shot with an Explora, custom loaded using standard fosbery slugs, that looked very good at 50 yards. Heavier, usually running 7 1/2-8 lbs (can someone confirm this?)

From an investment perspective condition is key.