Is it possible to make a Crazy Climber repro using an UNROM board by just swapping the 74HC32 IC for a 74HC08?
Yes, and that's exactly what Nintendo did back in the day. (
NEScartDB)
Thank you!
By the way, what's the correct mirroring of this game? I have a ROM with a Vertical one in iNES header, but in NEScartDB it's listed as Horizontal.
NEScartDB is almost always authoritative.
(anyway, look at the picture of the PCB in NEScartDB. "V" is soldered, meaning Vertical Arrangement, or horizontal mirroring)
Sorry this a bit late, but crazy climber can be wired exactly the same as any other UNROM reproduction, and all you'll need to change the 74-32 for a 74HC08. It's an exact swap, so just desolder the old chip, pop in a 74-08, and continue as normal.
Source: test board on my desk currently.