1.85:1, 2.35:1 or
Anamorphic or 4:3?
all of this has a bearing on what size your picture should be.
NTSC is 720 x 480
PAL is 720 x 576
non anamoprhic 2.35:1 NTSC is 720 x 236
non anamorphic 2.35:1 PAL is 720 x 360
Anamorphic 2.35:1 NTSC is 720 x 360
Anamorphic 2.35:1 PAL is 720 x 430
that's a starting point but you need to give us some idea of what your using etc for more detail.