Hello I just happened to find this thread via google looking for the an fitting sizes of the stock s2000.
I do not recall but are the fittings -8an and -6an from the fitting on the firewall?

I got the ls1 swap with AC in the car since about 2012/2013. I was also trying to do a california smog legal setup for years, but the only thing i have not solved was the EVAP. Im in the process of putting in an ls3/480 swap and reconfiguring the ac lines again.

old setup is camaro compressor plumbing tig welded to honda plumbing. had issues with ac cause the heater valve was not placed. it would blow cold but not strong.

new setup will be using a universal heatervalve and using aeroquip hoses and fittings. a sanden d7 type compressor using the dirty dingo low mount for AC. its the closest to the block. about 10 inches from middle of crank pulley to outside of compressor.

ill keep you all posted.