Which Zeiss 50mm lens are you thinking of using?
The Zeiss ZF and ZF.2 50mm f/1.4 lenses use a very similar 7 element/6 group design as the 50mm f/1.4 AI, AI-s, AF, and AF-D. It does use a 9 bladed aperture instead of a 7. The 50mm f/1.4 Milvus uses an updated design and tests seem to show it's considerably sharper at wider apertures than the older lens.
The Zeiss 50mm f/2 Makro lenses for Nikon all use an 8-element/6-group design, although at least one comparison preferred the Milvus. There's really no comparable lenses to these; Nikon's 55mm and 60mm "micro" lenses are limited to f/2.8, and the Tamron 60mm f/2 macro is designed for APS format dSLRs.
Finally, there's the 55mm f/1.4 Otus, which is one of the best optics out there. You get what you pay for.
Whether any of these lenses are worth the price is between you and your wallet. Based on how I use a 50mm lens, the value isn't there for me. I do own a Voigtländer 58mm f/1.4, which is also built by Cosina. Like the Zeiss lenses, it extremely well built mechanically, but I'm less impressed with the rendition of the out-of-focus areas. I also refused to pay the ~$90 for the "correct" lens hood and use a generic instead. My other two 50mm lenses are a 50mm f/1.8 AI "long nose" I've owned for almost 40 years, and a 50mm f/1.8G. Neither one of those lenses will win "high score of the day" on test charts, but I'm okay with that. The two Zeiss ZF.2 lenses I do own, an 18mm f/3.5 and a 25mm f/2, I feel are better than their Nikon counterparts.