I've used various Walbro in-tank pumps, Walbro in-line pumps, and a whopper SX Performance in-line pump. None of them would hold pressure for more than a few minutes. I've never noticed my car needing to crank longer in order to start after installing a different fuel pump either.
Fuel cells normally come with these one-way "check" valves or "rollover" valves that act as a vent and safety valve in the event of going rubber side up.
http://www.jegs.com/p/JEGS-Performance- ... 7/10002/-1
If you want to remove your charcoal canister and associated lines and so forth it would probably be best to use one of these valves so that the fuel tank can vent but still be safe in the event of a rollover or gravity deciding to switch directions.