Moore apparently was referring to the Thornton Freeway sign, which has highway numbers on it.
It could be Moore in the 1960s was familiar with the sign being called Thornton, but by the 1980s wasn't able to recall the term Thornton.
Moore wasn't side-to to the limousine, so his estimation that the President "had reached the Thronton Freeway sign" at the moment of the first shot would have been from an oblique view. It seems to work well with a first shot in the Z150s, being heard by some about Z161. A first shot in the Z200s would probably mean the President was blocked from Moore's view by the Queen Mary and the agents stood on the car's running boards.
The cluster sign stand you refer to could not be characterized as a "highway marker sign". The "RL Thornton Freeway" sign refers to a highway.
My Reply#23 says that Moore said
a small highway marker sign, in front of the TSBD.
The twin cluster sign stand a half car length past the signals has nothing but highway markers, about 14 of them.
The Thornton sign is not
a small highway marker, but as u say it has 6 little highway markers below.
Strange, the last time i looked at the FBI report it had two errors, it nominated the Thornton sign, &, it had Moore standing near the wrong corner, someone has doctored the wording.
Moore said he was standing 6 or 8 paces out into the intersection from the southeast corner.
And, he said he could see all of the action down Elm St, subject of course as u say to being blocked by Queen Mary & Co.
And, if the JFK limo had just then straightened on Elm, then the question of judging distance doesnt rear its ugly head.
Is Thornton a Freeway or is it a turnpike? Or is Stemmons a turnpike, praps a long way further north.
The furtherest sign says that there is some kind of turnpike before Fort Worth.
Oswald shot-1. JFK at distance one limo length past the signals. Ricochets off western side of western signal arm guy rod. Hull found at SN.
Oswald shot-1. Oswald fired at T137 which is say Z112, slug lands at T138 ie Z113, noise arrives at T139 ie Z114.
Max Holland says shot-1 was at time Z107-8.
Dale Myers says that shot-1 was at i think T150 or some silly such late number. No it was at T138.
Oswald shot-1. A spray of fine lead hits the back of JFK's head (XRays).
Remnant slug makes non-round hole in limo floor (photo), & probly hits driveshaft & road (& aint found).
The FMJ broke in 2 as is usual (CE567 CE569 found in limo).
Oswald shot-2. JFK at time & distance Z218 (the magic bullet)(found). Hull found at SN.
Hickey shot-1. JFK at time & distance Z313, blows some of JFK's head off (small lead fragments found in head)'
Hickey shot-1. Remnant slug veered 6 deg & cracked glass (& aint found).
Hickey shot-2. JFK at time Z316 (slug makes dent in chrome trim)(& aint found).
Hickey shot-3. JFK at time Z319 (slug hits tarmac Elm St)(possibly wounded Tague)(& aint found).
Hickey shot-4. JFK at time Z321 (slug hits curb Elm St)(possibly wounded Tague)(& aint found).
Hickey shot-5. JFK at time Z324 (slug hits grass)(& aint found).
Hickey shot-6. JFK at time Z327 (if Hickey fired 6 shots)(slug hits curb Main St)(possibly wounded Tague).
[edit][i have now established that it was shot-6 or at least the last shot that was the JFK headshot, ie shot-5 dented the chrome trim, shot-1 possibly wounded Tague etc.][see my thread Bronson Saw Hickey Shoot JFK.]
None of the 5 or 6 hulls are found. They must have somehow stayed in Queen Mary, & were picked up by Agents on the way to Parklands, & secreted.
The AR15 01 fired at 400 rps (but zero footages on youtube) & would have ejected the hulls say half the distance of modern AR15's which fired at 1200 rps (when autos were still legal)(lots of footages of ejections & ejaculations on youtube).