I'm restoring the rear drums and was wondering if these are original to a 70 ss built in February of 70?

Part number 3853714 with a T3 next to it, and either a 1 or an L and 179

Part number 3853714 with a T9 next to it, and a J 29 on the other side.

Also, I didn't look closely at them when I took them off, does it matter if they don't go back on the same side they came off of? The brakes were just redone and they were re-surfaced for the brake job.

Yes,those are assembly line rear drums used the 1970 SS Chevelle.I have an NOS boxed set here,with the part number #3853712 printed on the box,yet the drums have #3853714 cast into them.This is typical of some parts cast for GM,by their distributors.Always keep drums on the side they were removed from once they have adapted to the shoes.But if your drums are freshly cut,it should be early enough that they can go on either side.