@RustyRatRod
2" square tubing with 1/8" wall thickness they come in 20' lengths.
I am sure all large cities have wholesale steel suppliers. We have a steel supplier here about 80 miles away that I got my steel from.
So anyhow the in town local steel fabricating shops can order you a 20 foot stick of 2 x 2 x 20', they can cut it to your desired lengths so you can haul it. They probably have it on the shelf, very popular size.
Also you probably want a 10' length of
1 1/2" x 1 1/2" x 1/8 wall for making the engine mount stands. And something like 10" x 18" x 3/16" plate to fasten the bell housing to if mounting to an engine stand setup.
The steel fabricating shops usually have a pile of short scraps and drops that you can grab some of those for the other small brackets you want to make. Think they will sell it to you by the pound on the scrap.