Tips n tricks for exhaust install

If I recall correctly, that kit is made to fit your 108" wheelbase or the Dart's 111" wheelbase, the difference being whether you shorten the midpipe or not (and the size muffler you ultimately use).
I would mount up the headpipes, then loosely hang the tailpipes to make sure you've got plenty of clearance in all the right (tight) places. You may need to let the rear hang to get the pipes in, but set your position with the rear end supported.
Fit the mufflers to the tailpipes get the most clearance at your floorpan recesses, then you can determine the length your midpipes will need to be and how much to cut. Remember- measure twice, cut once.
Once it's all roughed in you can decide on your hanger layout.
Then tighten it all up, I usually work from front to back. And Rusty's absolutely right- some small jackstands or light-duty floor jacks make positioning the pipes a lot easier.
I don't envy you- I hate exhaust work too, since I don't have a lift either... these old bones take a while to get off the creeper nowadays.