I'm unsure about this one, but I can tell you there were 5 motherboards for the LC/Performa/Quadra/DOS-Compatible 630.
One of the boards was replaced by a later revision with a socketed 040 instead of a Surface Mount soldered type.
The Quadra 630 logic board is on it's own - so there may be a change in the ROMs which are on the solder side of the logic board, or there are some passive component differences which act like a 'switch', defining different boards.
The Apple hardware techpub doesn't denote what the difference is, and I can't find reliable information on the 820-xxxx-x screen print number. Also, they all identify the same "Gestalt" of 98.
The only thing I can think of is if it's running 7.1.2 you should ensure you have the "System Enabler 405" in the "System Folder" - Some motherboards require System 7.5.1 minimum.
For reference, here is the data I can provide (661-xxxx numbers are old service part numbers)
661-0158 (non-DOS) 1 SIMM Slot 68LC040 4MB Soldered + 32MB
661-0189 (Q630) 1 SIMM Slot 68040 4MB Soldered + 32MB
661-0234 replaced by 661-1114 (may have soldered CPU)
661-1114 (DOS) 2 SIMM Slot 68LC040 4MB Soldered + 1x 32MB + 1x16MB
661-1115 (DOS International) 2 SIMM Slot 68RC040 4MB Soldered + 1x 32MB + 1x16MB
Gestalt 98 (all)
Maybe System Profiler might give you the ROM ID and/or ROM Version:
Quadra 630 ROM ID = $067C
https://support.apple.com/kb/SP229
ROM Vers = $21
LC 630 ROM ID = $077D
https://support.apple.com/kb/SP247
ROM Vers = unknown
LC 640 DOS/C ROM ID = $067C
https://support.apple.com/kb/SP293
ROM Vers = $32
Perf 630 DOS/C ROM ID = $067C
https://support.apple.com/kb/SP287
ROM Vers = $32
Perf 630(CD) ROM ID = $067C
https://support.apple.com/kb/SP286
ROM Vers = $21