Prairie,
Was that standard Hi-8 or Pro Hi-8? If it is pro hi-8, you could get a smige more out of the image with good color correction. If it's consumer hi-8 it's like Grinner said, fuggeddaboutit.
As for your images being in 300dpi, it's all going to end up as 72 dpi in your NLE.
When it comes to DVD your only bet is Standard Def DVD. If you have good color correction, it won't look too bad onscreen with a digital projector. Don't expect any miracles. You're working with a low-res format and even if you shot it with the pro grade, it's still going to look like video. So don't get any bright ideas of 'film-looking' it in post. It will just make things worse.