Use a gas fired foundry, Google those words, you'll get a lot of anwers.
Zinc oxidizes very easily and quickly, which may be a severe problem at high temperatures. Adding charcoal to the crucible to scavenge the oxygen may help some.
And the fumes are indeed very, very nasty.
Would bronze (copper alloyed with tin instead of zinc) work for your project?
Brass melts higher, close to 2000 F. You need slightly different material for brass cast due to the higher temp.
There is minimal risk of zinc fumes as long a you have good ventilation, and the higher temps have there own risks.
How much are you trying to melt?
Casting brass is a job for professionals, it's not easy and it is dangerous (fumes). It is harder to do than with aluminium.
Use Wikipedia to find the melting points. Then judge for yourself.