See what the schematic or SM parts list says those 'other' transistors should be. My recommendation is to change them only if they are faulty - never mind if they are old and might be noisy - get the unit working first - then think about changing them.
Yes - 2sc693 and 2sc871(D)
can be substituted with ksc1845. I believe the only 1845's available now are the FTA suffix. Those are rated 300-600 in gain and will likely fall short of the 871's to the tune of 10-20% - at least in my batch this was the case.
Alternatively the 2sc2240BL has slighly higher hfe rating and will likely match closer to the 871's. Does it matter ?.....Probably not :scratch2: