Long, wide groove?

[Derek Cohen]

I need to make a long, wide groove down the middle of a 8" wide board to accept another 3/4" wide board coming in at right angles (basically making a really long T.)

How do folks do this? Is there a magic Stanley super wide plow plane?

Marking gauge it in and plow out the waste with a chisel?
Plow plane the edges in and then chisel out the middle?

It doesn't need to be pretty, it'll be upside down and hanging off the back of my bench as a tool tray mounted shelf.

Matthew, this sounds like an opportunity to practice a (tapered) sliding dovetail.

If you are up for this, then we can look at methods. It is fairly straightforward.

Regards from Perth

Derek