The DT is a fantastic engine. As close to a unanimous standard for MD Diesel applications as you will find. A block heater isn't going to do anything for you, in terms of WVO, unless you are going to retrofit it somehow to heat oil. The temp of the block is not important. It's about keeping that oil viscous and heated. Make sure that the DT has an "Inline" style injection pump. The rotary pumps (much older technology) are not as good with veg. My current bus has the rotary style which I will someday upgrade to the inline style, but if it ain't broke, don't fix it! Good luck out there, feel free to PM me or whatever with questions. I saved a lot of headache by having someone to bounce ideas off of for my first conversion, which was also on a DT466.
Patina enthusiast and professional busman