Is there a 4.35 retainer for a 308 front bearing. IDK. Back in 2001 when I tried this, I could not find one.
I'll tell you a secret; just use the longtail as is......
The longtail in my 68 Barracuda is awesome. Mine is a B/E body tail. I moved the stick back between the buckets, on a custom adapter plate I fabbed up; and up high enough to install the top shifter bolt from inside the cabin. Then I installed a really short shifter and fabricated new stiffer/longer/beefier shiftrods.
Now I can bang gears like a pro instead of like when I was a hi-school schmuck, banging knuckles on the dash. Since I did this, in lemmee think, 2004 or so, I have not missed a shift ever.
Yes the driveshaft had to be shortened, and
I had to extend the shifter hump, and the carpet didn't fit right anymore, and I had to grind off one boss from the frontmost pad which sets in, and interfered with, the T-bar Crossmember
But it was so worth it.
If you have a bench, obviously this may not work exactly as described. But, you should have buckets anyway, cuz without a good sturdy bucket, you can't do tricks. Well you can but NOT with any degree of control, or repeatability, lol.
Furthermore
a few FABO members have fabbed their own plates to move the shifter forward to the factory location. Thus the only change required was the shorter driveshaft.
BTW
yes the tail drops a lil lower than where the shorttail ends at, so if you get an incurable vibration, you can start by jacking the tail back up. Then proceed to resetting the pinion angle.