[hiccup]

You can pick up a copy of the Power Boat Guide for basic information about 1,000's of boats.  Here is what it has listed for that version of the 3600:

"Made from 1987-1996

Length w/Pulpit.....................36'8"
Beam....................................13'9"
Draft......................................2'11"
Weight .............................16,500#
Clearance...............................9'7"
Headroom ..............................6'2"
Fuel ............................... 396 gals.
Water............................... 85 gals.
Hull Type..................... Modified-V
Deadrise Aft ........................... 14°
Strong-selling express set class standards in her
era for versatile mix of hard-nosed fishability,
family-style accommodations. Highlights include
well-appointed interior with solid teak joinery, expansive
bi-level cockpit, top-quality construction. Original cabin
layout with island berth forward sleeps four; alternate
layout introduced in 1989 sleeps six. Entire bridgedeck
lifts on hydraulic rams for engine access. Conservative
lines still look good today. Standard 350hp gas engines
cruise at 18 knots; 375hp Cats cruise at 24–25 knots."

That version of the 3600 Open might be the quintessential Tiara in my opinion.  It defined the dual-purpose express.  With that said, it is a somewhat dated design with 14° deadrise and no prop pockets.  Tiara modernized the designs of the Opens starting in about 1992 (meaning all models that were introduced that year or later) by increasing the deadrise and adding prop pockets, which increased efficiency and reduced draft.  The newer models are better performers and sea boats generally speaking.  They were very well made boats though, perhaps better in some ways than what they did in later years.  

You're going to want to check the hull coring for water intrusion, and at that age I'd be thinking that the fuel tanks are on their last legs if they haven't been done already.  Wiring will also be showing its age and you will likely have to address that here and there.  The engines are pushing 30 years old, so it is all about how they were run and maintained.  By default, I wouldn't expect much more life out of them, and be pleasantly surprised if I was wrong.

Good luck!