Hey there,
I'm looking to build a bus conversion...seeking good recommendations for engine and transmission combinations, for a used bus. I'm not looking for a short bus, diesel is my preference.
...seeking good recommendations for engine and transmission combinations
My suggestion is to read through a bunch of the threads on this site. After a while you will have read about the various engines and transmissions available and their various pros & cons. There is a lot of very good information at your fingertips.