As said, the HPi report is not going to show anything. If you have the chassis number and reg details from a non recorded scrapped car on this then the DVLA will think it is the original donner car

The ID from this car is most likely from a scrapped S1 shell. This car has an earlier shell and so can not be an S1

It is harsh, but if you are convinced it is all pukka, then a full inspection from the DVLA with paper work to prove is the best bet.

If they say it isall ok then great, as a replica it is nice, but can't see how it is anything other than an S1 replica.