To get the long wool of an angora, you need a double recessive 'll' gene. (That's two lower case 'L's) First generation they would all be shorthaired but they would all have the ability to have longhaired offspring. HOWEVER, the resulting F2 longhaired offspring later would most likely be a disaster.
I've run across a couple of NZ 'angoras' because a lot of the meat breeders will add in some angora to get a denser coat on their meat & pelt buns. Occasionally, one would show up with the longer wool, not just the denser short coat. They didn't have the full angora coat structure, though, so all they did was mat up. Before they were even finished being groomed, they'd start matting up. I've only met two of them, which is a small sampling so maybe it will work out better for you with a Flemish instead of a NZ.
I've tried an angora x angora cross (English angora crossed with a 1/2 Satin - 1/2 German) and the offspring from that had matting issues, too. Unless there's some sort of really compelling reason to cross breed, I'd not recommend it, There is a Giant angora breed out there if you want a large fiber producing rabbit.
Although, if you're willing to cull heavily and eat a lot of rabbit, maybe you could get a Flemish angora breed. Which type of angora would you use? There's a Giant, which is already large although their fiber isn't the softest. The French & Satin have the fiber that makes a lot of halo when spun into yarn. Not the softest, but has a lovely halo. The Satin has the Satin sheen to it, that's a lovely thing. The English have the softest fiber, although not a lot of halo and they're the smallest of the regular angora breeds. There's the German which is larger angora breed, as well as the Chinese angora which is the coarser 'commercial' type of angora fiber.