Getting usable HD input/output with D-VHS without a computer?

[Electronic M]

So a couple of years ago I bought a nice working pair of JVC HM-DH30000U D-VHS decks. But aside from a brief functionality test I have barely used them...In addition to watching the tapes I have I'd like to use these decks, and the blank tapes I have, for occasional time shifting (thus making a PC an impractical/unreliable solution to IO conversion).

These decks are capable of recording 1080i HD (or really any digital data), but the only HD input they have is a stinking HDV/FireWire port; there isn't even an ATSC tuner(what were they thinking?!). And HD outputs are only marginally better with a choice of HDV or HD analog component video. At least you can get cheap converters to make Component into HDMI.

I can't get a cable box with HDV/FireWire output, only HDMI.
Anyone know of any early hDTV OTA tuners that have HDV/FireWire output?
If I could get such a tuner I could record OTA (and ATSC demodulators are getting cheap enough that I could get one to modulate HDMI from my system to an ATSC channel to record).

Also does anyone know of any HDMI to HDV converters or any HDV to HDMI converters?
I know Grass Valley made the ADVC-HD50 HDMI to HDV converter, but they are out of production and seem to be unobtainium(I'd like to be proven wrong on that). If there's any other devices out there I'd love to find them.
You'd think with all the nuts shelling out 3-4 figures for D-VHS decks someone would have made a bidirectional HDV converter with an HDMI input and an HDMI output for a couple hundred dollars to cash in on people like me...It can't be that hard.

I have to wonder how anyone even used these decks 20 years ago when the inputs make it VERY hard to record anything but SD NTSC.