Well, the first really oddball thing I've learned about the 394 is an oil plug that looks to need something like a T100 Torx to remove. So, like several before me, I used Vise Grips to get the goofy thing off.
So, did you replace yours with a standard bolt (and what size is this thing, 7/8ths?) or buy the tool needed to use the original plug?

 

There's a special 8-point bit made specifically for it, but a 1/2" drive ratchet will get it out easily. Use the ratchet itself. Extensions tend to slip in the recess.

Olds V8 thru 1967 used those too, so it's not totally off the wall, though I suppose to anyone used to a bolt-type drain plug it does look pretty weird.

I sure hate you used those vise-grips on it. Can't have done it any good. Just make sure its gasket is in place so it doesn't leak.

 

Ah, I should have looked closer, 8 point using a 1/2" drive on any 4 points, cool! Glad I get to reuse it, I actually didn't want a bolt being the lowest point on the car. I doubt the vise-grips warped it, things were tough in '61, time will tell.

Thanks!