Is the idea to save money? Like I said in email, a DIY 2-tank conversion can be done pretty inexpensively. This is a 'proven recipe' with millions of successful miles on it now. Statistically, those with issues/problems doing what you propose are exponentially higher than the success rate. Yes, the Vegistroke system is the cream of the crop - but there are other ways to skin the cat if you have some fab skills and patience.
Using the 'test ports' on the opposite end of the fuel rail from OE fuel supply to supply VO is CLEAN and relatively easy. You will add check valves (CV's) to the end of the factory fuel lines at the heads - this will prevent VO from entering the OE fuel system and is the only mod to OE fuel system. The VO system will be totally redundant - providing you a way to get home if you have a problem with either fuel system!
VO will leave a separate tank, ideally with a heated pick-up, and travel through heated fuel lines (TIH) to a pre-filter and a stock PSD pump ($40) located under cab. Then to a fuel pressure regulator (~$150).
The 'return' line from FPR will run through TIH back to just before VO tank. Tee the return into the suction line instead of dumping the fuel back into the tank. This will create a 'loop' for the fuel to travel that reduces strain on the pump and HEATS the fuel very well.
The 'pressure' side of FPR will then go to a filter head (~$15) where you'll use a spin-on fuel filter. I use a WIX 24006 filter (~$9). After filter, there will be a CV - this one prevents diesel from going to the VO tank when running on that expensive stuff.
Following this CV is a tee. One side of this tee goes up to the engine and the other side has a normally-closed 12v solenoid valve. This 'purge valve' allows diesel to flush the VO out of the heads and bypass the VO-side CV, etc - sending the VO (and a little diesel) back to the VO tank.
Tube-in-hose (TIH) fuel lines use coolant to heat the fuel by placing 3/8" aluminum tubing inside 3/4" heater hose. The tubing costs about $1/ft, heater hose about $1.25/ft and the 'ends' can be made for about $6/ea using 1/2" black iron tee's and nipples.
You switch fuels by turning the pumps on/off. It takes about 2 miles for me to get up to temp and switch to VO - then I burn straight VO as long as I wanna drive that day. The 'purge' at the end of the day takes about 20secs and puts a quart or so of diesel into the VO tank. I have gone as far as 10,000 miles on a single tank of diesel.
I can likely burn VO in colder temps than I could diesel (if I could get the engine started/warmed up). I have burned straight VO in -5*F with no problem.
There's a few more bits and pieces I recommend, but this is the meat and potatoes of my F350's conversion. I have 170k miles on the high cholesterol diet in this truck now and have yet to have the first fuel-related problem.