The second problem is that converting the circuitry to Verilog is straightforward, but converting it to usable Verilog is considerably more difficult. If you model the circuit at the transistor level in Verilog, you won't be able to do much with the model. You want a higher-level model, which requires converting the transistors into gates, registers, and so forth. Most of this is easy, but some conversions require a lot of thought.

The next issue is that you would probably want to use the Verilog in an FPGA. A lot of the 8087's circuitry isn't a good match for an FPGA. The 8087 uses a lot of dynamic logic and pass transistors. Things happen on both clock edges, so it will take some work to map it onto edge-trigger flip-flops. Moreover, a key part of the 8087 is the 64-bit shifter, built from bidirectional pass transistors, which would need to be redesigned, probably with a bunch of logic gates.

The result is that you'd end up more-or-less reimplementing the 8087 rather than simply translating it to Verilog.