Ok, here's what I'm thinking for the 300d, please poke holes in my plan so I don't screw this up!
I'm going to T the coolant hose as it comes out of the engine, 5/8 ID i believe, then use that to wrap my WVO filter as seen here,
http://voconversionbasics.websitetoolbox.com/post?id=3726199
Then I'm going to continue the coolant line from the filter to my FPHE, then back along the WVO fuel line until it reaches my heated fuel pickup, then back up along the WVO fuel line and finally T it back in to the coolant line before the radiator somewhere? Main concerns are these,
1. where should I T back into the line? It doesn't seem like a good idea to T back in right before the engine b/c then I'm creating a loop where the coolant never goes to the radiator.
2. Is all this (the heated filter, the FPHE, the HOH, the heated pickup) too much for one loop of coolant? Should I somehow break it up into more than one offshoot of the original coolant lines?
3. The FPHE I'm looking at only comes with 2 size fittings which are both hose barbs. Its either 1/2 or 3/4". Which one should I use? Is it a problem to neck down the size of the coolant line or increase the ID of the fuel line right before the FPHE?