Modifying my Barracuda to accommodate a 10.5 in clutch was time consuming but there is no economical High Performance 9.5 inch option available any more. I found that utilizing the normal Z-bar location was the best solution but required fabricating a bellhousing pivot bracket. When I first performed the upgrade, I decided that modifying the stock Z bar was out of the question as these parts are hard to replace. I was able to salvage other Z bars and modify them as described above. I made two different Z bars one for a diaphragm clutch which used the original 273 (shorter) clutch fork and one for a Borg & Beck clutch (10.95 inch MP scallop clutch) which uses the standard (longer) 10.5 inch clutch fork.
I mocked up the bellhousing pivot to be square and level to the A-body fender pivot and measured the required Z bar length to fit between. Its not necessary to modify the clutch pedal linkage fork on the Z bar but the clutch fork linkage must be fabricated to fit as close to the bellhousing as possible (while the pedal fork is attached to the actuator). After completing this work, I ran the 273 with stock exhaust for a year or so then upgraded to 360 with headers with no more interference issues than with stock 9.5 inch clutch.
I am currently running spitfire shorte Headers not TTI because TTIs werent available when it upgraded my engine but the stock exhaust opening was only changed slightly by the 10.5 inch clutch upgrade and the payoff is an affordable performance clutch and well worth the effort.
This mod took me a month or two to complete
Good Luck