I just use a homemade lever on the transmission that is a modified length that allows me to shift within the space of the stock 2sp console insert. I then cut and filed my own indent/lockout plate to suit... I did this 20+ years ago, still works fine, I can post a pic if you like...
No problem I happen to be replacing transmissions, the centerline that use on the linkage is approx. 2.75" ...do you know what factory bracket is? I'm guessing longer than 2.75" since that should give a longer throw on the shifter... I like the idea of not having to cut the 2sp insert or buying another insert, in particular since at the time i swapped my th350 and the glide in and out fairly often. To get a picture of the shifter lock out that i made, I'll have to pop the console out...
I've done it both ways - the way ak 67sd shows works fine for a 3 spd - but whenever I've done it, the shifter did not line up with the numbers (minor annoyance) but then I just modified the existing detent/lock-out plate. Making a new one would not be that tough. It was awhile ago, but I seem to recall using the stock linkage (no cable). I do recall changing the lever arm that connects to the transmission to adjust the length of the shifter travel - but it was a long time ago and memory is foggy.
When I put in the 700R4 I opted for the Shiftworks route. Their kit was great. Installed exactly like the directions showed and works perfect. The insert shows all 4 gears, numbers line up with the shift lever, can't get into reverse without pushing the button and the back-up lights/start-lock-out work fine. Looks like it came that way from the factory. The kit (as shown above) uses a cable rather than the stock shift linkages and required cutting a hole in the floor.
The "do it yourself" way is definitely cheaper. Shiftworks are not cheap (but much better at current exchange rates).