Is the engine in the vehicle or out ? I think that factory design was to have the engine upside down, and tack the cork pan rail gaskets to the block. Then set the pan on, with the rubber end seals attached to the pan. I usually try to install like that, and usually install some sealer on the pan before installing the rubber end seals. If I install sealer, I will set the pan on thee engine, get all the bolts started and snug the bolts. Then tighten the pan bolts the next day when the sealer is set. The gap you have now should compress when the pan is tightened.