Gnucap Newbie: did I come to the right place?

Hello World! I am a Linux user who wants to simulate and optimise an audio
amplifier before actually building it. When I was looking for a simulation
tool I found Gnucap. However, I am not sure if Gnucap is right for me.
Skimming through the manual, I realised that many things are not yet
implemented.

For example, the input stage of my amplifier is a differential pair made
from two 2SK170 JFet transistors. According to the manual, JFet devices are
not yet implemented in Gnucap. Also, even if JFets were implemented, I
don't understand how I would tell Gnucap that my JFet is a 2SK170.

It would be great if someone could shine some light on the status of Gnucap
in the context of my situation / needs.