Yes, there was a company- the name escapes me- that generally did Delta cabriolet conversions (circa 10 or so) back in the mid to late eighties leaving the four doors and window frames intact and a little awkward looking IMO- unlike the one off Agnelli integrale evo.
I believe they also did a couple based on the Prisma too. I've seen the Delta's in the flesh albeit not for a long time but only the Prisma in photographs.
No doubt someone can shed further light on this.