Congratulations, your latest varac 3.7.9 with 847rig now can handle the ft847 with PTT over RTS or CTS and CAT over serial-com.
Here the specific ft847 requirements as I have it working:
PTT and modulation must be on the same connector with ptt over RTS or CTS, and NOT ptt over cat
The PKT connector is ONLY for FM. The Data-In-Out connector is ONLY for all except FM, usually SSB. VaraHF uses Data-In-Out.
The circuit diagram in Yaesu-manual-(my page 16) has a wrong capacitor with 10uF in "afsk-out". I must use 0.47uF. With 10uF my ptt switches too slowly.