That's a £10k car in the current market. I had an SPI Cooper last year that had a £20k professional restoration, was not modified and £10k was all I could get for it, and even that was not a quick sale! That car has been advertised for a few months now...
with that level of restoration i'd have thought you would have people would biting your hand off for it.
Maybe an unpopular view but for £13k I would be tempted to get 60/70s, historic status carb car. Unless you are wanting to do serious miles or everyday use as I think they will hold their value better if things turn for the worst with low emission laws and maintenance is certainly easier. I agree £10K if current trends are anything to go by.
I have looked at 70s car but struggling to find anything that is rust free or doesn't need much work for similar money.
I have a few Mini's that will be for sale later in the year, will be around this kind of price, 70's and 90's cars. Feel free to get in touch if you want any more info.