IMO the stock fuel/return lines are to small for e85, even with an unopened motor. Using stock fuel/return lines that were used with 27lb. injector to going with 60lb. injectors and needing roughly 20% more fuel I would think would need larger fuel/return line and it wouldn't surprise me if the manufacturer of the pump required it. I'm not familiar with either one of those pumps, so I could be wrong, but I'd rather be safe then end up with a whole bunch of headaches. I've read about a lot of people using those pumps, but not much with e85. I went with an external Weldon for my application. That's what worked best for me. I would check just to be sure that larger lines aren't required. And even if they aren't I would never use the stock fuel/return lines with e85. Have to use a PFTE conductive core. Like belsie says, they're 27 years old, why would you not replace it. Also, if it's done right, one pump is all you need. I only use one pump.... Good luck with the conversion.