Try a Four Seasons 74803 instead - cheaper and more closely matches the original :
https://www.amazon.com/dp/B000C2Q92Y..._t2_B000C2Q8VG
Under 10 bucks so not a bank breaker if it fails again and won't rust out! As long as the vacuum causes the valve to shut to replicate the original action you'll be fine. You can check this by starting the car, putting the temperature on coldest and fitting the vacuum hose to the stub on the new valve - you could even make a hole in the bag just big enough to do this so that if for whatever reason it works the other way round, you can send it back in its original packaging for a refund.
Should be a clear plastic bag it comes in (hopefully) so you should be able to see the action by holding it up to the light. No vacuum allows the valve to open so if you're doing a coolant change, it automatically fills/flushes the heater matrix and vacuum closes it so you can shut off the heat for cold air coming in.
Like the ideea of a deep 13mm socket - excellent redneck engineering!
Here in the UK, domestic copper water pipe comes in 15mm and 22m sizes, the 15mm stuff is ideal for heater bypass emergencies!
