8mm film has more resolution than standard definition but less definition than HD (1920 x 1080 pixels). So scanning above HD is a waste of time and money. As the user requires for use on a PC it is not a good idea to output in ProRes. Whilst it is possible to get CoDecs that will read ProRes, it is an Apple only format and it can not easily be written from a PC. DNxHD is a format for high end PCs. Given that the user uses a PC with Windows Adobe Elements a lighter option may be a better option. Quicktime using a Sorensen CoDec may be a good option.
In terms of the actual transfer. You need to see samples of the work done by the transfer company. There is a huge difference between the high end and the low end of film transfers. A high end transfer company will be able to restore the footage so that black blemishes are not so evident. See [removed spam link] The company has been transferring film footage to digital for longer than most companies currently around and has happy customers around the world.
