bulkhead size anf flow question

[diastech]

i have a quick question about bulkhead size vs. good flow.

i have a 90 gallon used tank that i bought a sump for (megaflow model 3).

now the used tank i have has bulkheads already permanatly installed in it and the intake to the sump bulkhead has a inside diameter of 3/4 inch and the return has a 1/2 inch inside diameter.

now the sump intake tube has a 1 inch outside diameter. the return is all set because i have a mag 7 witch has a 1/2 innch diameter return tube.

i know i can always get a reducer for the intake bulkhead connection to the intake tube of the sump, but is that going to be enough flow? i cant replace my bulkheads because i cant redrill my tank without possibly cracking it. should i look into getting a new RR 90 gallon with a bigger intake bulkhead? like a 1 inch inside diameter?

thanks for your help.