MadaboutKitcars

i have acquired a partially built very well built mk kit car.
The kit is built with all parts direct from mk except for the engine/gearbox and rear drum brakes and the steering column. I have looked round the car and can find all major parts on their website. Unfortunately there is no receipts for the kit or parts as they have been lost. the previous owner has been building for 5 years in his garage but gave up
It has a 2L pinto engine in it with a shortened sump and twin webbers. But there is no water system yet and the loom still needs finishing for the dash and lights.
My question as I would like to make it road legal, should I buy a 2l ford focus and swap engine and anything else I can, will that enable me to use the reg from the donor or should I keep going with the pinto.
As new to this but having looked at the car I couldn't let it just sit there and die.
Any help appreciated

You can't use the registration number from the donor. You can use the donor parts, but that may give issues if they are from more than one donor (Q plate possibly as 'undetermined origins'). It has to go through IVA and the registration process, and if DVLA are confident the parts are from one donor source they then issue a registration number relevant to the age. eg If donor is 'B reg' it will get a different B reg plate to the donor. Without receipts you could be in for a difficult time - they like receipts!