Depends on what you mean by "hang in there."
Read the bottom section first.
If you mean hang with the competition, it won't matter what suspension you have if you're using standard or all season tires. I know this from experience. With bad tires you not only have less grip for acceleration, but you'll also have a lower maximum cornering speed and longer braking distances. This means you won't be able to use as much throttle or keep as much momentum as many of your competitors. In a sense, an autocross car is a machine with the sole purpose of getting the maximum performance out of a set of tires, constantly resting on the ragged edge of traction, and it's the driver's job to operate that machine at maximum efficiency. You need to get your set of tires through the course quicker than the next guy can get his through. So study, practice practice practice (at events), then buy your wagon some running shoes, and then practice a bit more. With those alone, ("those" being a good knowledge base and a capable set of tires,) you'll then be able to "hang in there" with a number of competitors. Not all of the cars that show up are fast in a straight line, many are stock, and many drivers are rookies.
Above all, don't forget to have fun. Remember that you're out there with a station wagon that was designed to haul anything but @ss, and don't worry about not keeping up. Especially your first time out. No matter how you do, someone is going to enjoy watching a woody wagon try to dodge cones.
----> Or if that's not what you meant, perhaps you just mean that you want your car to "hang in there" during turns and at least feel more sporty and confident. In which case, just get some new shocks and a stock-style set of aftermarket sway bars and call it a day! I also know this from experience. That's really all you need. Before I ever started racing, my first upgrade to my suspension was a set of sway bars from UMI. They only had one style of set back then and the rear bar was stock style. Heck, my front shocks were blown when I installed them. And yet I still thought my car felt incredibly sporty, and it felt like my ride quality didn't suffer in the slightest bit. I still use those sway bars to this day.
There's really no point in spending a few grand on suspension if you're only maybe going to autocross once. Put the money into restoration, brakes & drivability, then scratch the biggest itch. Whether that be power or handling. Just keep in mind that if you don't upgrade wheels and tires then there's no sense in handling improvements.
Sorry if this reply is excessive. I'm up way too late.