I have a 1983 Firebird S/E where I am replacing the engine with a 2 Gen 461 which is heaver (probably around 600lbs) than that original 305 GMC stock engine. I am needing new suspension to be able to handle the extra weight and keep the front end level with the rear.

Adjustable height suspension (pro touring style, independent rear) has been suggested in the past. Anyone have any recommendations?

Heidts was one recommendation I got

 

You don't need independent rear for almost any reason.
For the added weight, you can buy universal springs of a heavier rate, probably something in the 900-1100 range and trim to the height you need, or use weight jacks. The jacks will do the same thing, allow you to use a certain weight spring and adjust the height to your needs. They also make it easier to make changes later, set corner weights, ect.

Another cheap option would be trying a set of Moog iroc replacement front springs. They are rather stiff and usually make the car sit higher than stock with a sbc
So maybe it will be about right for you.

 

I appreciate the information, thanks