Engine 89 GT Thermostat replacement woes

FINALLY! Success! No leaks, runs normal!

I think the culprit was the thermostat, I think it kept sliding down when I reinstalled housing. For others benefit:

1/4 flex socket set was a great idea.
Goo-gone works well for removing old gasket residue
Wiped surfaces with isopropyl alcohol after brake cleaner (91%)

Used Motorcraft gasket and Motorcraft thermostat. I tried the “twist and lock” I saw on YouTube video that only applies when using a Motorcraft thermostat , it didn’t work for me.
Applied Permatex water outlet dressing to both sides of gasket (thin coat) Placed on water outlet.
Applied thin coat to thermostat housing and placed thermostat in. Secured with rubber bands. Burp hole at 12 o’clock position.

Let it all set for 20-30 minutes
Cut head off old bolt and threaded into top hole.
Installed housing and started bottom bolt
Removed “guide bolt”, replaced with top bolt.
Snugged bolts, to hold, cut rubber bands.
Tightened bolts
Wanted to let it sit 24 hours, was 36 by the time I got to it again.
Filled with coolant, “burped” and go.

Now, on to the other 99 problems I got, but a leaky thermostat housing ain’t one!

I’m pretty sure holding the thermostat in place and waiting for a full cure on the sealant was what made the difference, but perhaps the Motorcraft gasket too versus Felpro ? Any way, this part is done now. So happy to take kids for a ride in it today.