I dunno about the IDI, but pensecola has a horrible reputation with PSD injectors...
Many have learned the hard way about blending. The problem is coking from incomplete combustion due to the more viscous fuel failing to properly atomize through the injectors.
By using the stock 6-way valve for your dual tanks, you are slowly contaminating your 'diesel' tank with your blend - since all of the fuel in the lines, pump, fillter, IP, injectors, etc gets returned to that tank every time ya switch back to 'diesel'.
If yer driving that much, it won't take long to recover the cost of a 'proper conversion'. All ya need is a couple of 3way valves and some heat (heated fuel lines and a FPHE) and you can safely burn 100% after warm-up. If you are driving 200mi/day - you'll only use about 1gal of diesel a day. You can DIY a good conversion for your truck for under $500 and see as many miles on your old truck as it would get on dead dinosaur juice.
Keep us posted and like I always say, post pics of the carnage if it doesn't work out!!
VO is about the viscosity as diesel at about 160*, so thats the minimum temp you are shooting for in order to get the injectors to spray (atomize) properly. You can put honey in a windex bottle, but it ain't gonna spray right...
So yes, you need to heat the VO. A FPHE (flat plate heat exchanger) is a compact and efficient way to do this using coolant heat. We also use a TIH (tube in hose) design that puts our aluminum fuel lines inside heater hose - creating heated fuel lines. Heating the VO filter with a 'wrap' of tubing or hose and running coolant around it is another good trick.
What you really want is segregated fuel systems - VO in the diesel tank is not a good idea. Ya don't want to 'share' filters either - use a separate filter for the VO system. If nothing else, this gives you the opportunity to switch back to diesel and get off the side of the road if (WHEN) veggie filter plugs up.
The 3way valves replace the stock 6way tank valve. (one 'supply' and one 'return' for each tank and supply/return to the engine = 6...) When switching back to diesel, we switch the 'supply' from the VO tank back to diesel but wait until all of the VO is 'returned' from the fuel lines, IP, injectors, etc to the VO tank - then switch the 'return' valve back to diesel. Putting these valves close to the IP minimizes the length of fuel lines and reduces 'purge' time. (purge is removing VO from IP, etc before shutdown.
As far as good/best injectors - I think stock is best for your engine, but I admit I dunno alot about 'performance' IDI's. I know that engine will run for a loooong time with a good VO conversion in stock form...