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If you're not concerned with how the page reads then you're probably going to have to do a bit of research on it. ;)
38% seems to me a little high, but this is very reliant upon context.
Your best bet is to see what Google thinks of your current page and refine it accordingly.
(With regard your actual page. In my opinion 5 in links, 5 H1 tags, 10 in the body copy, 3 in alt tags might be too high for a 250 - 300 word page. It sounds like you might be pushing the keyword to the extent where the page is no longer useful to visitors)
Try a few versions with the keyword phrases in various concentrations (I use Bretts sim spider keyword analyser for this, edit post and analyse until you get the density chosen) and interlink the pages.
Use descriptive sub domains containing keywords where possible ( I know this doesn't count for much, but it doesn't hinder..)