I have a 1991 mercruiser 5.7L "bluewater inboard" (on a Malibu ski boat, 260 hp). It is carbureted with a (I believe) mercarb 4bbl (that or a rochester 4bbl, not sure if it matters, but it's 4bbl for sure).
The motor fires up great when cold, runs beautifully and has no issues whatsoever...