I've written a fair number of CP/M BIOS's and since I normally use M80 (Z80 & Z180) or ZDS for eZ80, I simply build the tables myself and don't use the DRI macros.
My $.02 is that if a programmer CAREFULLY reads Section 6.10 in the CP/M 2.2 Alteration Guide they should have a good handle on how to define these tables. The required disk information is basically the same for DRI macro use or straight DB/DW's and I find that building the tables myself allows for more flexibility and efficient use of memory.
As to the original question of a BIOSGEN: There is RomWBW if that's what you're looking for as a foundation. In my experience there's too many hardware differences between systems and I find it easier to reuse as much code as possible but every implementation is unique.
As to just a 1771 for disks ... while I built a BIOS with that controller and a genuine IBM 33FD in the 1970's, I've also used 179x's 765's, SD, CF, IDE, flash, MRAM, etc. as CP/M disks. As to DMA controllers ... I've used the Z80 DMA chip, Z180 internal DMA, custom CPLD controllers, etc.