Ok, all is better now; I have ordered a replacement clutch release bearing from:
Terrill Machine
Route 2, Box 61
De Leon, TX 76444
(254)893-2610
The price was $35 each (I bought an extra just in case) and $8 shipping. I am greatly relieved that these complete bearing assemblies are available. BTW, they advertise in Hemmings and carry all parts for rebuilding Buick engines up to 1966. From what I can tell they don't have a website.
On the issue of the saginaw length, I measured both the original T-10 and the saginaw and they are almost exactly the same. I will say that the saginaw is not an easy swap like I thought it would be. The linkage was a pain to setup (used a cheap Summitracing shifter) and the tranny mount is further back than the original. Most likely I will eventually install a wide ratio T-10 or Muncie, but that decision is down the road.
Thanks Jim and GSSizzler for your help, I was worried that I wouldn't be able to easily replace the part I had modified when I want to return to a T-10 (or Muncie), but that shouldn't be a problem now.