There is a brief history of the bike on the website. I understand the bike in question was used in endurance racing in France after the Daytona race in 1970. No doubt parts were changed or modified as is the way with racing motorcycles and its been restored. Hardly surprising then that it may differ from the original Daytona spec and lead some to doubt its authenticity. However, its the best we've got and lets be thankful for it. Its owner, Daniel Mercier is a good guy and he has helped me a lot in the construction of my own replica. As for the price of replica parts please be mindful of the time and cost it takes to make the patterns required to make copies and then for a very limited market. The outlay is considerable and parts may linger on the shelf for years. Taking one example, the front fender. I made my own using a fibreglass blade sourced in Sweden, which was relatively cheap, but the time it took to fabricate the bridge and supports was considerable given the very tight clearances. Taking into account the going rate for engineering work these days if someone offers you a replica CR750 front fender for £500 bite their hand off, it's a bargain. I'm sure Daniel is not making a living out of selling replica parts, but just like some of us on here has a passion for the CR750.
Eric
PS
If anyone is contemplating going to David Silver's 50th CB750 anniversary bash I'll be taking my CR750. With permission I'll start the thing so bring your ear plugs!