Hi CLT81R, Buzz here. At UAL i recall seeing the patches where 4 or 5 of our -61's had the APU for a while. By the mid 80's they were removed. Weight savings was one reason, poor access for maint. and not enough airflow to keep the pit cool was another. It was located in the fwd bulk pit, between the fwd cargo and the spar.
One of my NASA buddies flies the NASA DC-8, they have a good installation and they seem happy with it. At UAL they simply kept air starters everywhere the DC-8 was supposed to go.
Blow start one with jet blast? I don't think so... i'm thinking of the FOD damage, and getting enough air down the intake to get the N2
up to 25% or so. There was a "Jumper Hose" arrangement so you could fly a 727 in, drop the airstairs and have some good mechanics hook up the adapter, and a few lengths of air-start hose. It was useful where airplanes were stored and needed to be "brought to life" for a ferry flight to SFO
to complete the process.
Buzz Fuselsausage: Line Mechanic by night, DC-3 Crew Chief by choice, taildragger pilot for fun