Shot from bunches of helis. Even the small R22 and Schweitzer 300. They are tight but my 5'10" 220lb body had no issues. Unless you are shooting specific subjects like wild horses, boats or similar, I'd leave long glass at home. I carry 2 full frame bodies, one with 24-70 and the other with 70-200. Do NOT change lenses in flight. IS lenses will be preferable. Otherwise keep your shutter speed as high as possible. Helis shake like crazy and it's high frequency so you won't know it's happening til you get out and your body feels like it's buzzing. If your lens hoods don't lock, don't bring them. And if they do lock, tape them. Make sure cameras are secured to you. Empty your pockets, secure loose clothing and make sure your shoes are tied tightly (yes I have a story about that) The wind blast will catch you off guard and you don't want anything falling out of the Heli or worse, into the Heli and jamming the controls.
Most important...and I say this as a pro aviation photographer with lots of flight hours...do NOT ask the pilot to do anything they are not comfortable doing. Doesn't matter the experience level, if a pilot hesitates when you ask for a particular setup...don't push them. This is a quick way to end your life. As this is a "joy ride" with a fresh pilot I'd strongly recommend sitting back and enjoying the flight. Take pics as you want but let the pilot alone. Keep in mind you are a second set of eyes and ears and should let the pilot know if you see or hear anything unusual. Do a mission brief to discuss safety. This is critical.
Have fun but be safe first!!