Hopefully you can tell from Hutch’s photos that the fat spacer on the pickup clamp should be on the other end of the bolt taking up that large gap between the bracket and the clamp. I’d use red Loctite on all these bolts in addition to the lock nuts. I’m not a big risk taker.
Also you’ll notice that there is a fair amount of possible side to side motion with that center clamp. I took great care to make it exactly centered using the sump bolt holes as reference. As you offer up the sump you want to make certain that the pickup slips straight into that hole in the sump mesh. It can be challenging enough due to the big cotter pin on that part.
You can use sealant on that pump tube gasket if you want. I used Indian head shellac which is my go to for oil and fuel gaskets.
Double check that the coupler between the pump and dist drive moves exceptionally freely before sealing things up. It’s very easy for the pump to be tightened down slightly off center, even using the proper dowel bolts. I had to tighten it down several times to make it perfect.
Yes I suspect oil you put into the pump would run right out the pickup tube when the engine is upright, and when inverted it would run the other direction and drip out the filter housing which you probably won’t have mounted until you install the engine. I wouldn’t bother with it.