Hi
Copy your S8 reels (which would normally be 18fps) to 30fps.
I used to do this by making a direct re-film of the projected S8 on a screen using a 30fps VHS camera. (I didn't have a digital video then) Being shot at 18fps the projector had to be slowed down slightly to around 15 fps in order to prevent strobing of the image in the camera. The VHS copy was then digitised with an AD converter. Note: Projectors never keep a constant speed and one had to carefully monitor the strobing effect and adjust the projector speed to keep the dark band stationary at the top or botton of the frame.
At 30fps the VHS copy had 2 frames for each S8 frame. i.e. It had copied each film frame twice. At a projected rate of 15fps instead of 18,fps the change in speed of the action was only around 0.83 of the correct speed, usually not enough to make a noticeable difference. The stripe soundtrack (mostly commentary or music) was recorded separately at the correct speed and matched up during editing.
One loaded to VP and edited the export fps will make no difference to the speed of the resulting video as it will still play at normal speed and have the original duration.
To clarify.... if you export at 2fps (Yes you can do this), the video still plays at the correct speed but each frame exported is 1/2 a second apart along the timeline from the previous frame. (Try it...you will see what I mean) Obviously jerky! Set at 5fps for example every 6th of a second frame would be exported, and so on. (Less jerky!)
As your project has actual images that are different roughly 30th of a second along the sequence it means you can virtually choose any fps. above 15 fps to export your project and it will always export all the frames. (Not jerky!) To keep it even just click the Constant framerate box. If you wanted to reproduce exactly 18 fps you would need to speed up your project by 18/15 = 1.2% meaning you would set the speed change to 120 then export it with fps set above 18.
Nat