I'll definitely contact Henry at Williams to see what's possible for some of the cars he has currently in stock. He already gave me a few tips a year ago, very nice guy.
I know that everybody on here loves Williams, and rightly so, but may I suggest that it would be worth talking to Brands Hatch Morgan. They would be a lot more convenient for Brussels, being very handy for Dover or the tunnel. They provide excellent service too; the fact that Dave W drives all the way from Yorkshire to go there should be reference enough !!