A tip from a ship builder.
If the turret doesn't come off, as per Gino-
Drill a hole through the bottom of the hull and a matching one through the base, each slightly larger in size than an 8-32 or 10-24 or similar bolt.
Countersink the hole in the base a little from underneath.
Glue the right size nut into the hull using epoxy. Attach the model to the base with the right length bolt.
The model looks very nice so far. I like the idea of the concrete shells as bollards. It would be nice to do that for the model as well.
Our friend Keyda1 (Christine) in Aircraft has been building miniature models of a C-47 that she volunteers on, and is very fond of.
I pointed out to her that one of her photos shows a donation box made from an empty bomb casing at the base of the stair into the fuselage. She added all of that stuff to her first model of W7.
She's also put a lot of effort into replicating the current paint, and it looks really swell in a nasty sort of way.