You shouldn't need a pump.
They recommend a 110 size 4 stroke so perhaps a 120 2 stroke will be more engine than you need.
I would aim more toward about a 90 or so along with a pitts style muffler.
A tuned pipe would look nice slung along the belly but that would be more to set up and get working right. I am not sure if you can rely on muffler pressure with a tuned pipe and if you do use one you may need a pump.
I have used the Perry VP-20 Oscillating pump in the past with good results and you don''t have to tap the crankcase for it to work.