To be honest it's hard to put a price on a bare metal repaint on something like this.The main problem is knowing what the condition of the car is under the paint. Every repair that the car has ever had previously has to be redone. The car will need to be dismantled, removing doors, glass, boot, bonnet, trim, lights, bumpers etc etc to do it properly, which in itself is a lot of work. Then of course you have to strip the car to bare metal, either chemically or blasted.
Most bodyshops wouldn't give you a price per job, you're more likely to be given a price per hour, as they don't know what they're likely to encounter when it's all stripped. The minimum price of £5K is being very optomistic, you'd be better budgeting around the £8-10K mark. Again this depends on who does the work & how much they charge per hour.
Sorry for the doom & gloom, but it's better to be aware of the pitfalls with something like this. Costs can spiral when undertaking something like this, you could end up with a car costing up to £30K. For that sort of money you could buy something like my '69
cheers...Nige