You think that's heavy? Get a new one! The new Evinude ETec will be, minimum bare bones, 150 lbs. and goes up from there if you add long shaft, electric start, etc. and Mercury's 4-stroke will be a back breaking 175 lbs. to start!
And in truth, it's really not all that heavy, comparatively speaking. Yes, the 1970s era 25 was lighter, but it was also a wrung out motor that didn't have near the lugging power that your 25 will have. The '70s motor got its ponies from 22 cubic inches, while yours gets them from 31.8 cubes. The '70s model was screaming its guts out to achieve 25 horses.
And, size wise, the 1950s models were even larger! Of course, they were also almost 36 cubic inches.