Hello searat, I've got both of those kits in my loft awaiting completion of my current build.
I haven't looked at them in detail but I have in the back of my mind modifying them and building them by reference to the Boudroit 74 gun ship volumes.
As far as plastic is concerned I think they represent the only options for a 74, French or otherwise, pity I would love to do a 1:100 74 to complement the Heller Victory.
Given that the Heller/Airfix manufacturer no longer operates, that the kit is not in current production, after market supplies at 1:150 scale for these particular kits are likely to be a non starter with little interest shown by aftermarket suppliers, nice thought tho'.
Can the existing figureheads not be tweaked, to make them look a little better?
Good luck with your build and I would be interested to see your progress.