I believe the PCB from the Pennsylvania Flyer should work. Note that this is not LC Plus like this Topic's heading, just regular LionChief with BT. Both locomotives use the same boiler shell and DC motor (cs-6308661100-p).
Here's the link to the Pennsylvania Flyer Locomotive's parts list/ordering page> https://www.lionelsupport.com/...Loco-only-6803985001
$79.99 PCB part Number is : cs-691ENGM510-p; LIONCHIEF PCB / BLUETOOTH / 0-8-0 / PRR #6637 / LCBA 4.0
The $28.00 matching remote is Part Number: cs-6803984900-p Link here> https://www.lionelsupport.com/...hief-Set-w-Bluetooth
Or you could use the Universal Lion Chief Remote or the LionChief Bluetooth App.
Good Luck!
To get full function- chuffing sounds not just the background steam sounds, you would also have to swap out more components- smoke lever has to be the extended version to also trigger the needed IR chuff sensor. Then you need that matching 3 wire cable. Your smoke unit is also probably 27 or 30 ohms now, and for Lionchief control should be an 18Ohm resistor. Also, you might want/need chokes (part #12) on the motor wires for EMI/RFI interference with the radio module causing issues.
Parts #55, 33, 5, 40,
Complete Lionchief 0-80 parts listing as an example
https://www.lionelsupport.com/...Loco-only-6803985001
As much as i want to support and share repair and upgrade information- I'm just saying that from a practical standpoint, this can get costly very fast and is not really that effective in all cases- especially on the steam front, especially if you want chuffing sounds. Diesel can be done much easier and simpler and you don't lose as much function if you don't buy the extra parts (lionchief diesel doesn't have smoke anyway in any Lionchief diesel, and there is no sensor needed for prime mover sounds).
It's one thing to add Lionchief diesel to an RMT Beep or something. It's an entirely different ballgame on steam.