Any proverbial words of wisdom on doing or having an engine changed out.

My wife's 86 blew a rod at 250,000 miles. (seal around oil flange blew -
lost the oil - end of story)  Well that's not really the total story,
the oil light and buzzer went bad and constantly drove driver and
inhabitants over the edge.  After 3 months of it we had enough, replaced
the bad sensor.  When it began again my wife whipped into the local
quick lube and had the oil changed, upon leaving the buzzer started
buzzing again.  She concluded must be a bad sensor a-g-a-i-n,
approximately 20 miles down the road guess what happened.  That's right
a rod through the engine.  You guessed it the sensor is good.
Well I said all that to ask about switching a 88 2.1 into my 86 with the
blown engine.  My 86 is in better shape respectively and is an
automatic.  Should be a straight switch except my 86 has a newer quieter
muffler.
Should this be tried at home?  Any specialized tools required?  If I sub
the work out what kind of $$$ is reasonable?(I live near Greensboro, NC)
What are some things that the repair person should be cognizant about?
Head job?  Seller told me it uses about quart fluid a month?
THANKS,
SR
86 Vanagon Camper (not a Westy)
80 Rabbit Convertible
82 Truck Diesel (Rabbit)
88 Vanagon (donor-straight drive, picked up in Florida last week)