You can do the following and still stay F Stock:
1) Decide if you are going to run Autocross tires - If so then do this FIRST!
2) Mueller Frame Bushing Mod - (nobody would EVER know)
3) Urethane Front Sway Bar frame mount bushings
4) Front Urethane Upper and Lower control arm bushings. Likely have to tolerate a bit or sweaking. BUT for this class WORTH IT
5) Without he ability to replace the rear sway bar you will have to go very aggresssive on the rear shocks. I would recommend a 50/50 shock with the most agressive valving you are willing tolerate.
For starters you could try a PRO Street Stock
Oil Shock P/N SS201 they are 45.00ea from
Performance Bodies (1-800-722-4641).
AFCO makes a similiar shocks to above that have a low pressure gas charge (if you are more comfortable with that):
P/N: 1030 Medium valved
P/N: 1031 Heavy Valved
They typically run about $50.00 each
I have run both AFCO and PRO on dirt and asphalt cars and have been very happy with both. I am currently running the PRO SS201A
(adjustable) on the rear of my SS and have found that being able to go from 30/70 to 50/50 to 70/30 is no real advantage if you have to turn both left and right. Removing to adjust is a pain and the 50/50 works good!
I have never run the HAL (now QA1) shocks but I have talked to their tech folks and I don't think they will be the "best" choice for autocrossing a factory rear bar SS.
They do affer tuning ability but I'm not convinced they have enough overall valving at the right shock travel speeds to be the best "value" for your combo.
Only other option I know is to talk to Carrera - I am thinking of going to their shocks on the rear of my SS, front too maybe?
You will not be able to change the rear control arms but you can upgrade the bushings I would NOT go urethane in all of them DO just the Lower Arms and replace the uppers with MOOG Rubber. ALso remove the Rear spring insulators (rubber pads top and bottom of spring).
After you get the rear where you think it is OK start by swapping the front bar sizes. ED could be right that you may do better with a smaller bar. I think you can probably tune it to work with the F-Body bar though!
You will need a LOT of seat time to sort this combo out! Good Luck!