Choosing a/r settings for epics

[Phototaker]

I'm recoding some old movies made in the 50's & 60's most of which were widescreen epics what are on DVD's made using VideoReDo. When I import them into Handbrake I'm apt to get a video setting on 720x400. The preview appears as if the picture is squashed.

What I have then done is look up the pictures technical specs & see that the a/r might be 2.35. On the picture tab I have turned keep a/r & then take the 720 figure & divide it by 2.35.

What I wish to know is this the correct way to get the entire videos width? Since the height can only go down by increments of 16, I never actually fit the calculated figure exactly & I'm left with the choice like 304, 320, 336 etc. These figures preview much better than the original preview. Is this the correct way to go about doing this & is it just personnel preference about choosing a figure that is a little higher or lower than what might be ideal?

Is there any other way to tackle this like changing frame size?

Thanks in advance

[Deleted User 11865]

Use anamorphic Strict.