DIY USB CAT control cable for TS-850

My recently newly acquired TS-850 is a great radio. But what’s even more,
it comes with the proper serial ICs built in to hook it up to a PC for CAT
control. There are various ready made cables available on eBay to accomplish
this, but I really can’t get myself to spend $40 on a cable which can be built
for a lot less.
The serial connection on the back of the TS-850 (ACC2) provides inverted
TTL level signals. So all that is needed is a inverter and then a TTL to RS-232
conversion. At first I built the following circuit which I found here:

This is a straight forward circuit using the 74LS04 to invert the TTL signals
and then the good old MAX232 for TTL to RS-232. One could leave it at that
and use a USB-serial dongle to connect to the PC.
I went a step further and simply feeding the signals from the hex gate (74LS04)
into a FTDI USB interface. Total cost in parts ~ $15 and the satisfaction of
having built it yourself . Adafruit has a USB to TTL cable for just $9.95 which
would also work. I just had the other interface already on hand.
This is what my fancy design looks like:

One thing to note is that I did not use RTS/CTS which for some reason did not work.