I would be hesitant to run a 261 in a closed driveline vehicle. Those 261s put out a lot more hp and torque than the original 216s. IMO a 261 w/ torque tube is a disaster waiting to happen, and it won't take too long to happen. You have an added advantage of not having to change the lug pattern for a driveline swap. There are a lot more choices for a 5 on 5 or 5 on 4.75 lug pattern. Just my .02