snowman - if there is any debris / dirt in the float needle seat, it will not seal.

If you do not have a GM manual for this engine / carb - you would save yourself a lot of headaches by getting one. It will show you how to measure / adjust the float height.

Kudos for digging in and working on this at the ripe old age of 15 - I was tearing apart quadrajets and working on small blocks when I was your age and I learned a lot but like you - often didn't have good instructions or know the proper processes and I managed to dork a few things up along the way.

If it were me at this point - I would be saving for a new carburetor for this motor - there are lots of options and your best bet is to buy a new replacement model that has good instructions and a good reputation for performance and reliability.