Thanks for the information. Unfortunately I already purchased a 1967 250 inline 6 that runs good. It was aged to a 350 auto which I do not have. HOWEVER assuming a 231 or 250 will bolt up to the 216 bell housing and I can use the existing 3 on the tree as well as the closed driveshaft I will sell the 250 or use it for another project. We are looking for reliability and the drivability. From what I am reading keeping the 216 isn't a bad thing either. However we want to pull the body off the frame to paint it so that is the time to swap or rebuilt the engine. To clarify the 235 and 261 can bolt right up to the 216 (assuming we change the flywheel) and we can reuse the existing trans and driveline correct?? I don't mind swapping out the rearend gears either. Just want to make it as easy as possible (oxymoron I know) as this is my son's first major project. Any advice is appreciated.