Create a IFile {system level} via API - Powershell

Hi All,

Attempting the following:
1: Create iFile system level
2: Update existing iRule-> iFile referance the the file uploaded in step 1.

Im getting stuck at step 1, any assistance creatly apprecuated.
What I have tried:

Get Auth Token:

# Get API token
$big_ip          = 'https://[REDACTED]'
$url    = "{0}{1}" -f $big_ip, '/mgmt/shared/authn/login'
$body   = @{
    username = "[REDACTED]"
    password = '[REDACTED]'
    loginProviderName = "tmos"
} | ConvertTo-Json

$result = Invoke-RestMethod -Method 'POST' -Uri $url -ContentType 'application/json' -Body $body
$token = $($result.token.token)

Works.
Next, Upload my file:

$File_Name   = 'MyFile'
$File_Upload = 'C:\Temp\MyFile'
$url         = "{0}{1}{2}" -f $big_ip, "/mgmt/shared/file-transfer/uploads/", $File_Name
$filelength  = (Get-Item $File_Upload).length

$headers = @{
    'Content-Type' = 'application/octet-stream'
    'X-F5-Auth-Token' = $token
    'Content-Range' = "0-$($filelength-1)/$filelength"
}

$result = Invoke-RestMethod -Method Post -Uri $url -Headers $headers -InFile $File_Upload

Works fine too I am returned with:

remainingByteCount : 0
usedChunks         : @{0=46321}
totalByteCount     : 46321
localFilePath      : /var/config/rest/downloads/MyFile
temporaryFilePath  : /var/config/rest/downloads/tmp/MyFile
generation         : 0
lastUpdateMicros   : 1661257236246203

Next is where im stuck, creation of the iFile system level from the uploaded file.
Ive re-typed the below from the Curl samples here: Syncing local repositories and ifiles using iContr... - DevCentral (f5.com)

### Create a iFile {system level} - does not yet work
$File_Name = 'MyFile'
$url       = "{0}{1}{2}" -f $big_ip, "/mgmt/tm/sys/file/ifile/", $File_Name

$headers = @{
    'Content-Type'    = 'application/json'
    'X-F5-Auth-Token' = $token
}

$body = @{
    'name'            = $File_Name
    'source-path'     = "file:///var/config/rest/downloads/$File_Name"
} | ConvertTo-Json

$result = Invoke-RestMethod -Method put -Uri $url -Headers $headers -Body $body

Next I am recieving that the file cannot be found. So this query is incorrectly tructured ?
Translated these examples to powershell:
Syncing local repositories and ifiles using iContr... - DevCentral (f5.com)

Invoke-RestMethod : {"code":404,"message":"01020036:3: The requested iFile (/Common/MyFile) was not found.","errorStack":[],"apiError":3}
At line:1 char:11
+ $result = Invoke-RestMethod -Method put -Uri $url -Headers $headers - ...
+           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
    + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

 Any assistance appreated with the above & next up updating the iRule file refence.