If the bell housing is the same for the small block as for the 454, it
should work. Doing the swap, I'd go with an after market
transmission made to work on a 454 to be on the safe side. They
usually supply all necessary parts to bolt on the engine. the bell
housing is the key. A transmission for a 350 may not handle the
stress of a larger engine. Money ahead to change the tranny than
pay for a towing and tear down and then replace the transmission
later. When I put my 5 speed transmission in replacing the stock 4
speed, the company also sent a driveshaft to bolt on as the sizing
was different. Do homework and call the companies and they will be
able to give you what is necessary and the total cost.