Agreed with @okiecoiner about reinventing the wheel. If you're going to do this, do something new.
Here's a crazy idea - just blue sky here - no idea whether it's practical. Maybe the bioxrv.org model that's evolved in scientific publishing could be inspirational? When scientists publish their work it goes through a fairly standardized process. They start by submitting a manuscript to one of the many journals and an editor sends it out for peer review by several qualified peer scientists. The reviews come back, the editor makes a decision and usually, if the decision is at all favourable, the author has to make a detailed response to the reviews - sometimes including additional experimental work. Then it goes public - prior to that it's all private.
bioxrv inverts that. In this case, scientists post draft manuscripts of their publications on a public site before review. People who are interested can then read the pre-print and make comments, pose questions to the authors - there are often lengthy conversations. Often these conversations are between people who have never met before. After all this, the scientist can edit their paper and submit it to an actual journal. Or they can put another year's work into it to improve it.
There are all kinds of issues as far as scientific work is considered but it's a fascinating inversion and it's the most innovative thing that's come to the otherwise stagnant and stultifying world of academic publishing in decades.
I think something like this would be a very interesting match for coin grade - and that it would energize the hobby in general. I don't know about all of you guys but whenever I post something here I'm always very curious to see how it will be received and what alternative ideas to the one I post will turn up.
So, would it be possible to have a site where there's a grade description in text, maybe a few examples or maybe not, where people can submit their pictures of their coins. These would then be posted publicly and people (e.g. all of us nobs) could comment and make suggestions. There could be voting - coins would move up and down based on the cumulative vote. Or not - I'm not sure about that...
There would need to be some rules: the photos would have to be of sufficient quality - you could be quite specific about that. And any comments would have to be civil - there would need to be a mechanism to bar people if they act like jerks...I'm sure that's doable.
Over time, a sort of gallery of coins would be built upe. I think it would be super-cool and very engaging. I imagine the educational value for someone who is just getting in to coin collecting. It could have a fair bit of utility as well - I have a lot of coins that I would like to get graded but I typically reserve PCGS grading for coins that I think are worth it. That is, the grade would put the coin at a predicted value level that would be worth the expense of grading.
There could be various levels of editorial control of course - and for that matter you might need a sort of editorial board. There's a lot to think about...