Assuming the seal type characters are more or less te same in Chinese and Japanes for these old scrolls (true?), I tried to find them using this Chinese site:
It works in Windows and only using Internet Explorer.
First download this true type font:
Then click the file and hit install in the appearing window.
Now back to the search window.
The right part shows seal style character parts.
I chose 山 and 艸 apearing in the top seal of the kakejiku:
That gave no satisfactory results.
Then I chose 禾 apearing in front of the bottom seal character of the kakejiku.
The true type version misses the downward stroke to the left, but other seals suggest they are the same:
That gave no satisfactory result either.
It might work using other old style parts, but I did not recognize more.
Are there other free sites that let you determine seal characters?