I too have the "sagging on the drivers" side thing, but only between 3/4 to an inch.....still enough to bug me! You may want to confirm that it is your springs....I switched my rear springs side to side and even tried another set....no change. I believe the frame is slightly tweaked in the rear......only my back left is sagging.
As far as lifting it, I don't want to talk you out of it by any means, but I am completely amazed at what a stock CJ can do (off road). Because mine is so mint and a daily driver, I choose to keep it stock. I still go off-roading in it and have had folks come up to me and say" I'd swear you weren't going to make that obstacle." I disconnect the swaybars and get lots of flex from the soft stock springs. By running near stock sized tires, I greatly reduce the risk of breaking something. As far as self inflicted damage, in 13 years, I have spun both rear axle hubs (on the street), broke two small limited slip parts, and just worn out parts due to age and mileage.
To change speed here, I am building another Jeep where it's getting 3 inches of lift, front and rear 44's (late 86 and cut down Scout front) and 33's with either 4:10s or 4:56s....don't know yet.
4 inches will be a big change if your not used to it.
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon