I made one out of wood and made it wide enough that it would hold the body where the inner and outer rockers are welded together. I used some casters from harbor freight so I could roll it around when I needed to move it.
In the last picture it's hard to tell but looks like there might be evidence (maybe 1.5" from the left of the picture just above the drop rail molding) of some solvent pop. It could be a reflection from your garage though - hard to tell! When painting a small spot like that it is easy to go overboard and apply too much paint too soon.
Check the pickup(part that clamps to the plug wire) and the wire to make sure they aren't damaged. Often the clamp or the wire will get burned on the exhaust and give erratic strobes.
I use a generic cheap flaring tool and as long as I clamp it in the vise it makes pretty good flares. The hydraulic tools will make life easier though.
If you are looking for a direct replacement Inline Tube is the way to go. If you are looking to bend your own you could get some copper nickel brake line and fittings and bend your own pretty easily. I've done that on a few cars.
I've never had a problem with that much stall in a street car so I don't really see a problem with that. A 700r4 with e very upgrade available might last a while. If I wanted overdrive I'd either go with a 2004r or a 4l80E.
Just be mindful when you install them and tighten them slowly. It doesn't take much to distort the large fenders on the Monte Carlo. I had to elongate a few holes. If I was to replace them on a car that didn't need any body work I would go with the Monte specific plastic ones.
I checked the original line off my car against a store style o-ring assortment I have(the old kind where each compartment has a specific size of o-ring so you can buy just the one you need) and the one that seems to be the best fit has the following specs:
ID: 3/4
OD:15/16
Thickness: 3/32
The original o-ring is very compressed and flattened so pretty difficult to tell its original dimensions.