1964 parts manual at this linkhttps://mymopar.com/parts-manuals/
I see the pan you mention listed. But there doesn't seem to be a pickup specifically called out.
There are three 426's in 64. Std, Maximum Performance, and Hemispherical.
You have the Std version, which is how the pan is called out.
But for the pickups only the Hemispherical is specifically called out.
Then there is one listed as "w/o pipe, w/426 cu. in. engine" this is the strainer only for the Maximum performance swinging pickup, the pipe is called out as another part number.
2206261 seems it may be it but not specifically listed as to what engine it fits. Looked at the 440 Source listings and they gloss right over this issue.
Sorry I can't help more.