Age-related conundrum

[axle]

I had this confusion as how to retain the donor car reg. After consultation with DVLA I was told if I use the engine & gearbox of the donner car with a brand new chasiss ( even home made, with the proof). Then I would qualify for an age related plate, the V5 document will act as a proof of your donner car major parts.
Hope this is of some help!!!!!!!!!!!!