Mak 4 and 1 1/2" stand pipe question

[newgeek]

I know there are threads about this topic and I think I am just looking for reassurance here. I am concerned about my overflow not being able to keep up with my pump here are the details, Mak 4, 5 feet head and the overflow has a 1 1/2" Durso stand pipe. I did a test firing with the new sump I built (leak/pressure test) with a new Mak 4 as the return and I am blown away at how much this unit puts out so I am a little concerned the stand pipe will not be able to keep up. Anyone have experience with a similar set up? Thanks everyone.
Have a great night,
Kelly