You installed a used overdrive transmission and you have clattering and grinding. It's been my experience, having rebuilt 9 of them last year and 5 this year that they are generally well worn. You likely have bad bearings and worn syncros. There can be problems lurking in the overdrive component as well.
You cannot get more speed out of an overdrive transmission with the overdrive locked out, it would still be 1:1 which is the same as the transmission you took out.
The capacity is slightly less than 4 pints.
Fred
