I do not think there are any standard on pressure for the 17A Hornet along with many other wildcats. It should not be loaded to any higher pressure than a standard 22 Hornet. With that said, I am sure that people push the envelope with their wildcats. If you keep it loaded down to 22 Hornet pressures, it should work just fine in a 158. Ever consider a 22K Hornet? In my opinion, it is a much better round than the 22 Hornet. You get a little more velocity, but that is not what appeals to me the most. Since it has a real shoulder, you can head space off of it making it a little more accurate and you get better case life out of it too. Basically the 17A Hornet is a necked down 22K Hornet so the 17 gets the same benefit of the case design as the 22 K Hornet. While the 22K Hornet will never get the same velocity as a 17A Hornet, it does not do badly. I get about 3150fps with 34 grain bullets out of a 20" barrel and pressure is not outrageous, it is in the same category as a standard 22 Hornet. I shoot minimum charges of powder with the 22 Hornet and I only increased it 3.3% for the 22K Hornet which is a maximum charge for the 22 Hornet.
The 17 Fireball (or 17 Mach IV) is a necked down 221 FB whose parent cartridge is the Remington 222. All cases that have a .375" base are based off the 222 Remington or a stretched version as inspiration. The 222 Remington is an original design, and many, many cartridges have been based off of it or a variant, such as the 222 Magnum, including the 223, 17 Rem, 221 Fireball, 6mm TCU, it is a long list. The 222 Remington is to small cases as the 30-06 Springfield is to the larger cases.