Rather than put a Hard Top on a sports cruiser of that size why not buy one with a hard top on, ie another make?
Firstly Hard Tops weigh quite a bit (up to 250KGs). If your boat is not built to take it then this will affect the handling because of the higher weight than designed.
In my opinion you are much better buying a purpose built Hard Top such as the Peche promenade type boats or a Scandanavian beuty such as an Aquador
Also consider that Manufactuers struggle to make Hard Tops good looking so with a self built one the odds are against a decent looking boat!
Any good GRP company can do it (Osmotech at Port Hamble for one), but it will be very expensive and IMO it will look awful. Much better to sell it and buy a scandinavian hard top.
Before we bought the Rio, we looked at the Fairline Mirage which is a sort of hardtop-with-sunroof affair, and a few hardtop steel boats, but decided they would be a little stuffy on a summers day.
On the downside, the soft top we have is lovely in fair weather, but I'm sure it will be dribbly and draughty on a cold wet trip.
Those sliding roofs are pretty versatile though, I'll bet.
Never had a hard top boat. I've helmed a few and don't like being that closed in for some reason. Mind you, with the recent weather I wonder at my own sanity.