1) Stock piston & Rings can be used
2) Time saving
3) You may get warranty (not sure - could some one pls throw light on this?)
4) Better life - Rebored one loses its mechanical property
5) If the old engine was repaired earlier (opening the head, say some 3~5 times) there are possibilities of thread damage (this is my personal experience on my friends M800 engine) which you can avoid on new sub-assy.
Useful tips here from all. I suppose a sub assembly is best installed at an authorised service centre.
My 800 engine block cracked in two just after it came out of a Maruti Authorised Service! Got it resurrected at home, with an in house mechanic using a second hand engine block. Of course, it's got terrible wheezing and arthritic when starting up.
Am considering a selective overhaul so that my wife can continue to use it as a city runabout: engine overhaul, suspension overhaul (maybe just a change of front shocks and rear suspension) and some underbody patchwork.
Can somebody recommend a good place to get it done in Chennai? Either authorised or private multi-brand garage?