Rich, it might be worth adding some sort of gutter trim to cover up those cuts out
Just lob them out prior to paint (although it would still require the twin gutter rail if correct) then again there are soooo many cars like this that took advantage of the Tax exemption. My guess is that non of the 1970 vehicle exists other than the plate.
To the purist this is a huge hurdle but to someone wishing to own an awesome little car then they will overlook the fact (or even acknowledge it) and pay top dollar, many have sold on eBay for what I would consider silly money but in the same breath have seen loads recently for sale at over the 3.5k mark but they remain unsold, to add I have just purchased a genuine 18k MPI cooper in perfect untouched condition for £2250.
Price it right and it will fly off your driveway.
£1.5-£2k realistic, £3k if a buyer has loads of cash and not bothered about a genuine 1970 historic car.