Its a rather easy conversion. You need to use the 216 motor mounts, the 261 will not work, the bell housing from the 216 has to be used, not the 261.
The water pump needs a shorter shaft, you can modify the one you got, I bought new from Patricks and it was built for this conversion. Hopefully you have the full flow oil filter, that was standard on the later 261, but you can modify that by drilling some holes if its an earlier model. As the previous posts mention, there is a lot of information out there on this conversion. I had a perfectly good 216 and made the conversion, now I will be able to run it on the highway.
