I just installed my MAC shifter last weekend and I am still giddy about it. The shift quality improved drastically. I would start with the MAC shifter first, that may save your tranny from further damage. With over 140,000 miles the T-5 is probably getting beat up inside worn synchros etc. Start saving for a T-5 rebuild I paid $575 to have mine rebuilt and it was quite wiped out with a blown out main cluster etc. If you get it rebuilt before something breaks the job is much cheaper of course.
As for the clutch, maybe a cable change would be usefull even though this sounds like a tranny problem. Not too expensive or hard to do. The adjustable quadrants are really for aftermarket clutches, my stock quadrant works just fine and I have the stiff FMS clutch, with a new cable, though lots of guys report that they broke the stock quadrant from racing etc..
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Frank W 90 5.0 LX Notch MAC 2.5"cat bk FMS alu ds, MSD coil, MAC shifter 2.73 gears
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