Firstly, unless you are planning to somehow install this in a head, you’ll have a tough time accessing the block as the 2.8 V6 block is all aluminum and doesn’t have the typical freeze plugs as other engines might; it has a few drains, a few plugs for oil passages and that is about it.
Secondly, where are you that a heater is necessary? This engine has started up perfectly in -10 to 110 degree F weather without issue aside from a weak battery in the cold.