Dave it strikes me. (willing to be corrected) that your Bilstein dampers do not have enough compression available. Trads need around 216mm. (closed length) & 305mm in extension. However all morgans are different.
It looks worse than it is in the video because the bump stop was sat in the mid position on the damper rod, so the gap looks deceptively small, far smaller than it really is in fact.
For the record Monty's suspension has 41.37mm of travel at full droop, that's actually quite a bit of rebound, but he currently only has 18mm of compression travel plus an estimated additional 5mm of bump stop compression to give a rather poor 23mm of compression travel. To put this into perspective an MX5 offers 53mm if compression travel, so Monty currently relys on his compliant sidewall Continental Eco Contact tyres to give him a half decent ride, but the new brackets will solve all that by giving me back the damper travel I lost

I definitely lost damper travel with the lowering blocks fitted, although it must be said Monty does ride very well now and obviously way better than when he did when fitted with Morgan's appalling springs and a set of knackered AVOs. The truth is it's only when I'm really pressing on over a bumpy roads that things get interesting, and let's not forget we're not exactly living at the bleeding edge of suspension design here, what we're working with is a big old heavy cast iron beam axle (with diff) supported by cart springs controlled by a small pair of telescopic dampers.