Absolutely not a good idea below are the points why
1. There is no oil film protection on the sleeve to prevent rust, oil will drain of to sump and there will be chances of mild rust on the cylinder sleeve. That is the reason manufacturer usually stores engine blocks with special oil applied to sleeves. pistons to sleeve tolerances is about microns of an inch slight rust cause lot of problems like compression losing when load applied not in idling, oil consumption etc.
2.Even after honing and glazing also you can not achieve proper cross hatch pattern to retain engine oil film
3. Its already 70k run engine already scored, there can be microscope rust formation, more to that piston is at one position for about three years there can be chances of ridge. There may be other ridges too.
4. You run don't run engine oil absorb moisture, due to temp differences moisture is formed on the sleeve and other internal components and promotes rust. If you run car regularly moisture in the engine oil is burnt off.
5. Crank shaft and its bearings, importantly crank shaft thrust bearings may have rusted. A slight variation in thrust bearing play specification which is specified by manufacturer will give you lot of problems in future, like premature oil seals failure, flywheel and failure and total engine longevity.
My suggestion
you can go for oversized pistons and other related parts with MGP genuine, two sizes available.
My zen covered 2 lakh km on stock engine still going like new I like the car so I have purchased new half engine for my Zen from MGP distributor for 32K and kept it for future. I was told that time that esteem half engine also same rate. If half engine not available you can buy separately, engine block 14000, pistons standard 2500, rings standard 1500, crank shaft 12000 approximately and its bearings and can be assembled at any good MGP service point.
-suryaputhra