[chevyrestoguy]

3"/3.5" is a bunch of "Z", and you might have issues in a few areas. If you're planning to use the stock steering box in the stock location, your steering shaft is going to hit the top of the driver's side control arm. The steering linkage might get a little weird, too. The idler arm may not be long enough to secure to the passenger side framerail because it's now 3" to 3.5" higher than normal. If you're not running the high hump cab, you're going to hit on the transmission, and you'll need to build a new tunnel. You're going to need to build another trans crossmember, or space your current crossmember up a whole bunch. You'll have to keep an eye on your driveshaft angle and space up the carrier bearing. I'm not sure, but you might be real close on the brake booster and the heater box if you try to get the valve covers off. You'll also have to get creative on the front sway bar. The stock front sway bar brackets on the frame are too low in relation to the 3"/3.5" height change of the lower control arm attach point, and the sway bar will be at a downward tilt and won't be in it's optimal location.

After a lot of figuring, we decided that a 2" Z gave me the extra crossmember clearance without a whole lot of hassle. I will have to put a very small c-section in the upper control arm for steering shaft clearance. I had to redrill one new hole in my idler arm so it would bolt up. I removed the front sway bar hangers and bolted the mount saddles directly to the frame. I have a high hump cab, and I have plenty of trans clearance. I had to build 2" spacers on my trans crossmember and I also built a shim for the carrier bearing to get the pinion angle back to stock. With a 2" Z, you can still use the stock inner fenders if you trim the bottoms.

If you decide to Z the frame, make sure you move the whole assembly forward 1" at the same time to center the wheels in the wheel openings. The farther you lower a 60-66, the more the wheels move back in the wheel openings. A 1" change in the wheelbase makes a huge difference in appearance.

Z'ing a chassis gives you a lot of great features for hardly any money at all. In this case, more is not always better. You can send yourself down a rabbit hole where you wind up modifying everything, and it may get to a point where you regret your decision.

If your ultimate goal is to lay frame, you might want to consider that the rockers and bedsides hang way lower than the frame. If the body hits the ground first, then laying frame is a moot point.