Hola Mr. ParkCentral -
xxx
You are forcing me to scratch my old head.
But I might lead you into the right direction here.
xxx
I flew the DC-8, long ago, but never the 20/30 Series with JT-4A engines.
The ones I flew were 55, 60 and 70s...
But I also know the JT-4A engines, flew with them in 707-320s...
JT-4A is a machine converting fuel to noise. Excellent engines, by the way.
They performed super well, at higher levels FL 350/390...
The fans JT-3D ran out of guts and ideas above FL 350.
But all that goes back as far as early/mid 1970s. I have to try to remember.
And I threw my old manuals away...
So bear with me.
xxx
I remember the JT-4As running around 4,000 lbs/per engine in cruise
So, a DC8-32/33 would have been cruising at some 16,000 lbs/hr.
KLM and Martinair used to fly them.
xxx
The DC8-50s I flew were cruised at .80 Mach. The DC8-30 would be same.
So that would have been 460 Kts TAS or so.
The distance EGPK to CYQX is about 2,000-2,100 NM on NAT tracks.
So it would take a Diesel-8 some 4:30 to 4:45 to fly that sector.
First hour, takeoff and climb, would have been 22,000 lbs.
Three hours of cruise would have burned a total of 48,000 lbs.
Descent and landing would have burned 5,000 lbs.
xxx
I would volunteer to say they burned 75,000 lbs total on that sector.
They would have carried 20,000 extra for alternate/reserves CYJT.
Configuration passengers FY would have been 150 pax. All economy 180 pax.
Typical cruise at FL 350 back then.
xxx
Winds - If unknown, guess 40-50 Kts winds average over the NAT.
So might cost you 5,000 lbs extra westbound, save 5,000 eastbound.
xxx
You owe me 2 Grolsch beers for the effort.
Proost, en tot ziens...!

Happy contrails