STYNX55 -- 350 Mags are the "workhorse" engines. I would dare say, better than 60-70% of all boats on Winni currently (20'-26') have one.
As far as hours are concerned, take a look in the forum archives for the Poll that asks "what your average engine hours" in the past season.
http://www.winnipesaukee.com/forums/...ad.php?t=19941
Take that and multiply by your 19yr. old boat. For us, we run on the high side averaging 90 - 110 hours a Season -- but admittedly that is quite a high average.
For me - a 19 year old boat, with
ONLY 400 hrs. (avg. 21 hrs./yr.), would make me start asking other questions -- was this the proverbial "Grandma's boat only used on Sunday's to go to church? -- Was the original engine replaced ? -- is that 400 hrs. on the dash gauge or off the Engine chip? (if you replace the gauges say at 600 hrs., the dash gauge begins at zero from there)
Bottom line -- do not be so concerned with Engine hours as much as the Hull, interior, etc
.