Ron, from my understanding, regarding the R or Q code, in the torino cobras and Mach I's of '69 and '70, both were 428 CJ motors, same block, crank, and heads. The Q and R in those cars determined what type of hood /air cleaner assembly they got, helping to build the car on the assembly line. The Q code got a standard closed type air cleaner, the R code got "ram air" with outside air induction, on the mustangs it was the shaker scoop.
There was another option called the super cobra jet, and this engine got a different crank, connecting rods, engine
oil cooler, adn either 3.91 or 4.30 rear gears. You could get the SCJ motor in either a Q code or R code car.
The 428 CJ block had extra ribs in the main web areas that passenger car 428's didn't have.
I don't think they ever put 428 CJ's in any T-birds. 1967 and 1968 GT500's used the 428 police interceptor, while the GT500KR came with the 428 CJ. In 1969 and 1970, all GT500's came with 428 cj's or 428 scj's, so they didn't call it a GT500KR anymore.