What is limiting for you is the wattage you are asking. Those high of watts means very high amps with a regulated mod. 140 watts is 70watts per battery, wanting to run that high or are forced to do so due to an inefficient tank like Smok provides in their kits, you are going to need a 3x or 4x battery mod to gain any reasonable amount of run time. Battery technology for 18650 batteries is what it is, you can have high mah but lower CDR, you can have higher CDR but lower mah, or a balance of the two, can't have both camps, just can't fit that much power and energy density into such a compact storage unit.
120 watts and below (or 60 watts per battery) - Samsung 30Q, Sony VTC6, or LG HG2 all 3 3000mah and about 20amps CDR
120 to about 150watts ( or 60 to 75watts per battery) - Sony VTC5A 2500mah 25amp CDR, or the LG HD2, HD2C, HD4 (2000 to 2200mah) at 25amps CDR
150 to 180watts (75 to 90 watts per battery) - LG HB2, HB4, or HB6 1500mah at 30amp CDR.
Your settings, the Watts formula looks like this
140watts set/6.0v (3.0v per battery) lowest voltage supply/90% Control Board Efficiency= 25.9259amps you are needing and lowest voltage, so that leaves you in the camp of the Sony VTC5A 2500mah 25amp CDR battery for your needs and have any run time at all.
To gain more runtime you'll need to sacrifice the watts you are running down to 100 to 120watts or like I stated above you need a 3x or 4x battery mod like the Wismec RX200, RX200S 3x battery mod, or even a Smok GX350 4x battery mod.
Probably not the answer you were wanting but it is what it is, no getting around the limitations of the batteries we have available.