Swapping 340 into 64 valiant. Center drag link hitting oil pan

Yes, the center links (drag links are a completely different animal) on early As are different between slant 6s and V8s. You appear to already have the "drop center" V8 link, the slant units are straight across.
Now for why it's rubbing- what EXACTLY are you using for motor mount brackets/insulators?
If you are using what the parts catalogs are calling the correct insulators for '64-'66, they're most likely WRONG. For some time now many listings have been calling for the 2266 (or some version of that number) insulator which is WAY too thin for early As, but they are the correct mounts for the '67 and later As.
View attachment 1716208025

What you really need is the 2338 mount, which is thicker and locates the engine correctly.
View attachment 1716208026
Using the later motor mount will cause your engine to sit too low and rub on the center link exactly as your pictures have shown. It will also cause all sorts of interference issues with headers and linkages...
If you cannot find the correct rubber mounts, there is an alternative- a mid '90s truck mount.
View attachment 1716208027
Rather than reiterating everything, just read this link:
https://earlycuda.org/techdocs/JimBowenTheHolyGrailofMotorMounts.pdf
Going this route also has the advantage of a built-in torque limiter, so you can get rid of that rattletrap torque strap.
Thank you for all this.

Do you know? The part number for the mount on rock auto ? I cant find it