If of any interest to you, here is the TSFC of some engines...
Sea level, max takeoff power...
xxx
CF6-50E (747) = .36
JT3D-3B (707 - DC8) = .53
JT8D-7A (727 - 737 - DC9) = .58
JT3C-6 (old 707, old DC8) = .74
CJ610-4 (Learjet 20 Series) = .99
xxx
Happy contrails