What year 145? Front door panels from a 240 won't work with the vent window doors. Luckily, 1974-77 140/240 doors bolt right up and can use the same door lock cylinders, etc, from the original doors. You will have to either modify the door panels or the inner door skins to accept the corresponding armrests. Added benefit, if car is a 1968-72 model, you gain the side guard door beams. Also, power mirrors or late 240 mirrors can be installed, if the car needs to be updated more.
Front seats, you'll either want to weld the seats to the 140 rail assemblies, or use 1974 140 rails bolted to the 240 seat frames. I would do the former if you're tall. If average or short, the latter works fine. Rear seat will need to have the matching latch hardware swapped over, if pre-1974, and you're using a 1974-86 style seat back.
Hard to tell, but there are 240 black leather seats shown in this pic of my old '73 145E. Car also had 1976 front doors on it, hence the mismatch in paint color. It also had 1975-80 wiper arms, the 240 black A-pillar antenna, and a 1981 245DL tailgate installed.
Of the 145 model years, the 1974 is the most 240 parts compatible year, since it has the same rear floorpan section as a 240 (with different suspension mounts, obviously), so it can use the cargo panels from a 245 as well.