Bill Schwab wrote:
....
+----+
| A |
| |
| +---+ +----------------+
| +--+ |
| |
| +--+ |
| +---+ +----------------+
| |C D
| B |
+----+
....
The outer dimensions look like they will be roughly 1.6" square and
0.49" thick. The notches in the sides of the T are the part that have
me going. I could either clamp the T with A-B parallel to the table
(giving my rounded notches), or I could clamp with A-B vertical, giving
me the (preferred - sorta) square notches.

Your description isn't quite clear. Do you mean that this part is cut
from a block of steel that is about .5" x 2" x 2" and the stem of the T
is about 1" wide ? Much of your description could be interpreted two
ways, making advice difficult, but if you say how far from the bar of
the T the notches in the stem are, how wide/deep/long they are, and
how wide/long/thick the bar and the stem are, and whether the following
is a correct view from the end, perhaps someone can help.
+----+
| |
| |
|----|
|....|
| |
|....|
|----|
| |
| |
+----+

-jiw