A couple of points. The T56 Magnum XL has a separate bell housing. If you need a SFI approved bell house the 6060 is more difficult in this regard. The T56 Magnum XL does not need extra springs in the shifter for centering. The shift rail has a spring loaded detent roller that holds the entire rod in the 3 N 4 gate. This provides the tension you feel when pivoting the shifter to the 1-2 or 5-6 gate. The detent spring and roller can be serviced without taking the transmission apart.
By the way, almost all the parts inside the 6060 and T56 magnum are interchangeable.
The T56 I mentioned above is not the same as the T56 Magnum [XL] , so scouting around junkyards for a t56 to adapt will have the shifter issues I mentioned.
I had been corresponding with Tremec about swapping a t56 magnum XL tail housing, shift rail, and mainshaft . [It is not possible]. I wanted to keep the road racing ratios of my T56R which aren't available for the Magnum.
I modified my shifter [not the remote] by changing it to a Camaro T5 base with the delrin ball. Then I stacked 5 x Belville springs [diaphragm springs] on top of it.
SVT cobra shifters have a flexible [rubberized?] cup and a steel ball. The cup collapses [the Camaro T5 and the SVT T56 shifters interchange]
As you mentioned here ^^^^ get a Magnum XL [if you need a scattershield] or a TR6060 , they shift a lot better as-is [my T56 is now really good / fast / precise , But it took some work]
I have a friend with a TR6060 in a 50's Chevy pickup. He got the Trans cheap because it was missing the shifter off the rear.[just the top cover] We made a direct throw shifter off the back of the linkage cover similar to F5000's McLarens have. The shifter is lightning fast and very accurate, but vibrates.
Always use a reverse lockout. On my race car I removed the spring and added a solid tube [so it is impossible to select reverse] I have a button on the L/H side of the steering column.
On my friends pickup, we used a cheap "Summit" rpm switch set at 2200 on 4 cyl mode [= 1100 RPM on a V8] because the lowest we could dial in was 2000 on the switch. The RPM switch has normally open and normally closed
to ground modes. We used normally closed so the lockout is working correctly below 1100 RPM [when above this it locks out reverse]