The normal thing is to re-bore in steps of 0.020".
That gives engine capacity of:
+0.020" = 1293 cc
+0.040" = 1310cc
+0.060" = 1330 cc
Once a 1330 cc engine needs a further re-bore it is best to sleeve back to 1275 cc.
These are all normal standard service re-bores for a BMC A-Series 1275 engine and are not considered as modifications for insurance purposes. Pistons are all available at sensible prices (the 21253 is a good one to use with the 8.4 cc dish). Some say that the 21253 is not suitable for high CR's and/or high revs, but I have used them at up to 10.5:1 CR and 7000 rpm (not sustained revs).
If an engine is re-bored beyond +0.060" it is necessary to offset the two centre bores to keep sufficient block wall thickness between bores 2 & 3. That makes any future sleeving back expensive and possibly impossible, so it is not something I would ever want to do unless building an engine for out-and-out competition where block life is not an issue and saving a few tenths of a second per lap is what is wanted.