Here's my order:This is all great feedback, thank you. I tried searching but could not find this type of response. I agree car is not just a bunch of parts slapped together, that's why I'm asking. Ultimately I will upgrade the power, 300ish HP is my goal for a DD. I'd also like some bigger wheels but not going with anything bigger than 18, maybe even 16 or 17. The overdrive trans is for a steeper 1st gear and better highway milage. I might not get there tomorrow when I pick up my car but I can't afford to do all the work at once. So maybe the rear gear is not my next change. Maybe its the wheels/tires. Thanks again.
Decide on what engine trans you plan to run. Then decide what brakes you need to control it and be happy with where you drive.
Once you know that, then buy your tires and rims. Certain brakes won't fit behind certain rims. Lots of guys prefer thebappearance side of thing before the drivetrain just for affordability purposes and to have different different ride/handling.
Next up I recommend thinking about suspension and exhaust. A heavier engine in a worn out v6 suspension is no good. Likewise, a planned exhaust may be possible to start using before the swap, or at least can be budgeted ahead of time so it's on the shelf for the engine.
Then it's transmission time, because the old stocker often dies behind a new engine.
Knowing what valve body you're running you have a toss up. If you KNOW that your engine will grenade the rear end, you may as well upgrade ahead of the swap because what's the point of dropping tons of cash into something you can't drive or it'll pop? Likewise, no point in installing a brake upgrade when the rear is about to be swapped? If your engine plan is set in place you can run projections on a dyno calculator to have an idea where powerbands roughly lie. Typing in tire size, trans, and different gear ratios will tell you what rpm you will turn at different mph. You can pick which gears you want based on where you want rpm to be for how/where/speed you'll run the motor and your power bands on the motor.
Like the exhaust, think cooling. Maybe get a bigger radiator, maybe electric fans, things like that ahead of time. It's money you'll spend during engine installation anyways, so, do some work ahead, save time on swap weekend.
Then, go for motor last and it'll be a quicker easier install. You've already got rims that will clear bigger brakes if you want them. So on so forth.
Obviously depending what you run and depending what engine you want some steps can be skipped. A 305 car can use the factory exhaust on a 383 engine upgrade. Not the best, but functional to get going. A 350/290hr engine won't kill a 7.5 rear quickly unless you're really abusing stuff, so on so forth. But it's a good order to go through a checklist on.