Late to the TKO600 party, but the Ford version is usually either 0.64 or 0.82 5th gear, WITH long input shaft.

Generally a $200 charge for the shorter input shaft...
Generally a $150 charge for the spacer...

Put the saved $200 toward a new QuickTime 6057 that is available in a deep depth.

RM-6057 7.050 FE deep (60's truck bell)
RM-6056 6.425 FE short (60's car bell)
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Difference 0.625 or 5/8"

As the FE w/short bell + TKO-600 puts the shifter about 3/4" of an inch forward of the Mustang position, the 5/8" deeper (truck) bell puts it about where its needed WITHOUT the expense and confusion/flex of a spacer.

Many driveshafts have enough spline movement to handle the 5/8" change, but should be verified.

Had issues with the shifter and you may too.   The stub attachment point was too high, ended up in the boot, didn't allow the bend to start low enough, was generally IN THE WAY.    Had a box of a "no stub" design made with hole for the stock style shifter shaft.    This is a game changer for the shifter and will solve your issues with a little fabrication.   Hurst could likely be welded right or left, right, forward, aft, sideways to get your shifter on the correct path down below the boot.   Or make it a real sleeper with a stock shifter handle & knob!!   If you get a TKO, I'll send you a "no stub" for grins.

If you use the 0.64 OD make sure and calculate out the speed vs. cam in 4th & 5th as its a long shift.

Roger