First of all welcome to the site. Looks like you got your self a problem for sure. There is a adapter for just this problem for 64 and earlier blocks. It is pricy though and is sold at Butler performance for about $249 bucks.
BTC-P010004
Adapter to mount starter on 1964 and earlier blocks when using a later transmission
$249.95
-- Edited by Beaumont4008 on Monday 2nd of August 2010 09:41:47 AM