By following the thread below, you may find some info that may interest you. Although it does not pertain to the Mopar small block specifically, it might be of some use. Please note: The R154 5-speed transmission from the 88 to 92 Toyota Supra Turbo has the same bellhousing bolt pattern as the AX-15 gearbox found in the Dodge Dakota pickup. They are VERY similar since they are both manufactured by the same company (Aisin-Warner). The bellhousing from the 3.9L V6 will allow the R154 to be bolted straight up to the 318-340-160. All that is required is a custom pilot bearing, a 21 spline clutch disk and a custom driveshaft. Anyway, take a look.
http://www.v8buick.com/showthread.php?s=&threadid=2153
One does get tired of spending crazy money on Tremecs and such.
Greg