I have an assortment of test bends in sizes larger than 1". 90s, 45s and 30s with start of bend and length of bend marked on it and a couple inches of straight left on each side of the bend. There's always pieces of drop or mistakes around that they can made from. Helps to plan hoops and other pieces to get the fit I want. I don't think Loews or anyplace like that sell what you want to use. Pipe and tubing are two different things, both size and material wise.

Cage Gage looks like a nice tool. I've always just used a protractor. I have a variety of those in different sizes and configurations. Typically I'll pull it to within a degree or 2, check it and then just touch it up to get it exactly where I want it. Might take a couple of test fits but that's better than trying to pull a few degrees out of 1.625 4130.