I just got 4 1 inch bulk heads cause I'm getting both tanks drilled with 2 holes instead of 1 just for bac up incase 1 gets clogged or something
Just to clarify - it is the sumps you are drilling, correct?
And you are drilling so that the two sumps can be connected together?
Are you still going to have the two return pumps (one in each sump) and just using the connection between the sumps to keep the levels even?
If all of the above is correct, then the 1" bulkheads should be fine.
Drilling with the correct bit is easy - I prefer using a drill press, but it is not completely necessary.
If I were doing this, I would connect the tanks using flexible pipe (spaflex), and use a true union so the sumps could be separated and possibly removed for cleaning/future modifications.