Hi Matt and welcome.
The rules for registering a modified vehicle are a mine field here , I am on my second engineer now as the first was intent on being difficult .
My current engineer is practical and actually makes sense , he is not just looking to relieve me of money so I am learning a lot on what you need to do and what you dont need to do .
Panels wise there is a few guys here who sell them but they ultimately all come from the UK and the sellers will demand a premium for the service of you buying them here .
I buy all mine from the UK because I find it cheaper but its certainly not easier .
Hope you go down the cossie route , they are my fave engine off all time and go like a scalded cat .
For a 30 plus year old engine design to be capable of what it is and still outperform most 4 cylinders today is testament to Cosworth
Downside to them now is there scarce and guys who have them want a kidney and liver in payment but if you have driven one before you know what I am talking about.
If you need any help with anything PM me .
Bruce