Citrus3000Psi, from the Shmups forums, has posted on Reddit asking whom would be interested in his HDMI mod.. hop on there and give him a shout! I for one would be down for this mod, as not all tvs have vga input.
Here is the Shmups forum concerning this topic
And the Reddit post
https://www.reddit.com/r/dreamcast/comm ... mi_output/