driveline pitch?

i picked up a Walbro in-line pump for cheap on Craigslist and was wondering if it can be fed with the stock pump while not activated/running...i was thinking of activating it under boost only with a Hobb switch/TPS...are these pumps flow through when off or to much obstruction??..thx,mike

so my tranny is mounted way too high and im going to lower it but i want to know wat the correct pitch for the driveline is....any info is appreciated