Toyota Repair: Head Gasket, head gasket, radiator fluid

Question
I have a '95 Toyota Pickup 4x4 with about 180,000 miles.  I took it into the shop after it started vibrating slightly, produced white smoke from the exhaust, and started to overheat.  I was told that the head gasket had failed causing it leak radiator fluid and cause the smoke and overheating.  My mechanic said it would be very risky to fix the head gasket with that much milieage on the engine because something else may fail, other problems maybe encountered when fixing the head gasket, or the bottom may blow after tightening the top of the engine.  He suggested replacing the engine with a used one or getting a new car.  My question: is replacing the head gasket that risky with my amount of mileage?  I would like to get at least 2 more years out of the car.  Also my mechanic found an engine with 86,000 miles for about $3,000.  He has quoted me a price of $6,859 to replace the engine.  This includes all labor and parts for replacing hoses, cables, timing belt, cooling system, etc.  Is this high?

Answer
is it a 4 or 6 cyl?
sounds like a 4cyl.....being it's only one head gasket.
if so the price is way out
i just did a 6cyl- on a 4-runner  junk yard engine w/ new belt and water pump and rear main seal installed (44,000 miles on the engine) total price was Just over $5000.00
i think your mechanic is ripping you off... i would look for the engine my self and take it to another mechanic if possible.... if this guy is an indepandent tech his mark-up on the engine is 100% plus labor and misc parts.
if it matters i work in southern florida at a very large toyota dealer. good luck