For wet-printing chromes, there is no direct replacement. You really either need an internegative or a scanner. If you were slightly insane, you could enlarge your chromes onto 8x10 chrome film and pull the first developer to get the contrast under control. That's going to be a very very expensive approach though given the $10-20/sheet cost.
For making display transparencies however, there are RA4 options like Fujiflex. They require a C41 negative as source, but they produce enlarged transparencies for backlighting.