mercury outboard 1976 lower end. 3 cyl, 65 hp long shaft

[Slamcity]

Hi,
I have 1976 mercury 3 cyl. 65 hp model 650 long shaft
the powerhead is cracked.
I was talking to a boat guy and hes said that my lower end is common on lots of motors,
he said its better to find a good powerhead from 45-70 hp range, within the 70's
and swap my lower end on it.
Can anyone confirm this?
and what I should be looking for, any specifics?
I m new to this kind of stuff.
Thanks

 

[igotit]

I have a early 80s 35 merc and a 96 40 4 cyl mariner.
Almost everything interchangable.
Merc was like dodge.....ran same chassis layout for years at a time.....just different look