Got a problem.

After 2 months of sitting in the yard, I got the clutch working again on the Datsun. Just needed the system bled.

But now I'm noticing my front right brake is possibly seized.

I drove it about 20 miles or so, to clear off the rust that formed from sitting, and see how it drives.

When I drive, it pulls slightly to the right.
When I brake, it pulls hard to the left. So I'm guessing there's definitely something up with that right front brake.

Pulled off the wheel and couldn't get the caliper to move off the rotor. I could barely turn the wheel by hand(s) (with all my strength, which granted, isn't much)

Checked the other front tire, it turned just fine.

So, I was planning to replace the pads, since they're cheap, and see what happens from there. But I can't move the caliper, so I can't replace the pads.

Any advice?