I suggest you ask yourself what are you looking for in a boat.
The Venture/MacGregor 25 was built as a light boat. The intent was to design a light weight, economical, small sailboat that could go at 6.4 knots yet be pulled out of the water and trailered home.
These design features means the boat is not designed for big water and ocean passages.
That said the owner was known to put a big outboard on the stern and drive it out of the bay into the ocean and back to prove it could be done.
adding weight may make the boat less tender, yet compromise the sailing and trailer function of the boat.
Not saying you should do it as I feel it will compromise other positive features of the boat. It is your boat and I will follow the project with interest.