Clutch Issues - No Burnouts

Get a torque strap to keep the motor from moving under load, all four speeds should have one.

Get your numbers off your bellhousing and call Brewers performance to make sure you have the right Z-bar and bellhousing bracket for the Z-bar.

Make sure your clutch disk/flywheel is not contaminated from a leaking rear main seal or input shaft radial seal at trans.
Contamination will make your clutch slip.

Yes you could be hooking really well, but your clutch seems to be the weakest link here.

Check your throwout bearing too and listen for a whooshing noise while driving with clutch disengaged and in gear, usually 25-35 mph will reveal this noise if the adjustable rod is keeping the throwout bearing too tight against the pressure plate.
You should have a little lop in your pedal, maybe 1/2".

I'm leaning toward contamination first unless your Z-bar and linkage is way off.

I have a grease fitting on my Z-bar and on my steering coupler so I can shoot grease in there and keep it lubed without having to take everything apart- very simple, easy investment.

Dude, I feel your pain because I am in the exact predicament with my car, even have the line lock installed and still no burnout on dry pavement.
It will run like a raped ape on dry pavement, and bust the tires loose on wet pavement but doing burnouts is out of the question, clutch just slips.

I know my problem is definitely contamination as my input shaft is worn and fluid is leaking past the radial seal.
Brewers has a helper sleeve for this.

Also I have high compression and my rear main is seeping.

I have just learned to live with no burnouts and crappy launches.

Not dragging it so not really a big issue, but c'mon every muscle car should broil the tires at will right?

Good luck dude, and keep us posted on your findings.

Oh, and my clutch is a diaphragm style McLeod unit and I am using the over the center spring.