The latch anchor IS smaller than the door "hook" by design, so it will not bind. the door needs to move slightly independent of the cab. Real tight, and it will stress the cab wall and door. you need "slop" the "slop" is now take up with fresh-rubber door gaskets.
New rubber will:
Let the door move (over bumps, uneven terrain ect) and expand and contract keeping the door seal complete and stop the rattling.
If you have the door closing tight with no help from new rubber, that's not so good.
1986 F-150 Flareside 4x4, 351, 4-v, ZF5 speed. AC, Cruise, Tilt, Slider, Digital clock, Radio, Lariat seat, Pwr doors/locks