I have a 49 chevy fleetline and I am going to swap out the original 216/ 3speed with a 250 and a s10 t5 trans. I already have the motor and trans but I'm not sure what bellhousing I need for this swap.
what size flywheel are you planning on using, 153 or 168 tooth? Any V8, '63-up L6 or 4.3V6 bellhousing that has a 4 11/16" center hole will allow you to put a T5 behind the 250, but some work better than others. You need to pin down the flywheel size first before you go any further. Do not use anything from a '62-67 Nova. Do not use anything from a V8 Monza. These have the wrong fork angle. Whatever you end up using, the fork angle will not work right with the stock linkage. If you keep the '49 fork and the part of the linkage that bolts to it, I have a part that will allow you to finish hooking up the linkage so that it works correctly.
I assume you are aware that you must also do a rearend swap? The stock 3 speed is connected to a enclosed driveshaft torque tube style rearend. T-5 requires an open driveshaft. The 250 six has the same bellhousing bolt pattern as V-8's. So as suggested by Snarl you have many options.