success!
the overflow is 1/3 full and no leaks as you can see
(that small puddle there is from last time and does not want to dry)
i made a small plastic gasket for underneith where the plywood was a little uneven to help make a more solid seal. i also was a lot more careful with tightening the bulkheads properly this time and i didnt do any of the plumbing underneith until i was sure they werent going to leak.
i only had a very minor leak coming from inside the pipe (have no idea why cause its tight) but i think its pretty irrelevant as that water is just going to be going back into the sump.
im going to leave this overnight to make sure its good before i finish up the rest of the plumbing!