What's a good starter suspension system that can be upgraded later?
Someone correct me if I'm wrong, but I believe you want to install the subframe connectors with weight on the wheels; engine and tranny installed etc.
You're not wrong, but I've heard a TON of different and conflicting ideas on this one. Some say that the car should be leveled on jackstands, others install them with the car upside down on a rotisserie, or even
sideways on a rotisserie.
If you're installing them with the car fully assembled, it makes sense to do it the way you described so you don't have to redo all the body fits. If the car is apart, you have to hang and fit all the panels anyway. I've seen folks install frame connectors every way I've mentioned above, and haven't heard of any of them having issues. I think the only wrong way to do it would be to chain the frame to ground and apply some kind of hydraulic force. And even then, I can think of certain instances where that might actually be beneficial...
As far as the mismatched parts go, it really depends on the parts. Upgrading springs and torsion bars without adding sway bars isn't a big deal, the car will handle better than stock. Same with adding bigger torsion bars and springs and leaving the stock hockey puck tires on there. The car will still handle better. Now, I wouldn't install giant new torsion bars without rebuilding the front end, replacing all the bushings and tie rod ends etc. The new springs and torsion bars with old shocks might make things a little interesting, but I'd bet it would still handle better than stock. Might ride a little weird though .
I would
definitely upgrade the brakes before I upgraded the rims and tires. 9" drums barely work as it is, they don't need the extra rotational weight of say, a set of 275/40/17's on the front. And you don't want to find out that the new rims and tires you just bought for the car a month ago won't fit because your new disks changed the track width of the front end (and they do).