Hi Inga IV is a full size yacht.
https://www.facebook.com/Inga-IV-Classic-Yacht-for-sale-256791811498028/Not sure if the full size yacht is still for sale.
I have seen photos showing mast detail and the kit model is either a simplified model or the prototype has been updated.
So not a class but a single full size yacht which has been re-created as a model. I have one myself and she sails very well. I recently was lucky enough to come across a new set of sails and this is what she has now.
There is room for much detail on the deck and the original sail set up is better than the one you have illustrated which is a not very good attempt at a gaff rig, which this hull would not really have ever had.
Plans for the kit are relatively easy to find and it is worth seeking them as if you like a bit of woodwork and marquetry then you will enjoy it.
The engine is optional mine has an electric motor. You do not need much power to propel a yacht and you will never overcome the effect of the wind on the sails so regard it as a way of recovery when the wind drops.
The group up north are experienced sailors of this hull and my old set of red sails went to them a few years ago.
Personally I would ditch the current mast sail set up as it does not do the hull any favours.
Best of luck
Roy