First get a 1725 engine if yours is a 1592. The recommended maximum you should rebore the block is 40 thou which will give you 1775cc but Hepolite pistons are also available in plus 60 thou and even plus 90 thou(!) which will give you 1789cc and 1823cc respectively.
This is a very worthwhile increase and involves no extra cost over that of a standard rebore. The Hepolite piston part number is 18861/K 0.060 or 0.090.
That was the easy one. For those of you wishing to go further it is possible to go to 1922cc by using 1500cc Avenger pistons of diameter 86.1mm as against the piston diameter of 81.5mm.
The following method of installing these pistons in an Alpine engine was developed
several years ago by Swaymar Race Engines of Leatherhead (Tel: 037 23 79495). They tuned a 1922cc engine to give about 200 bhp and installed it into a Rally Escort. They said at the time that it was cheaper for them to get 200 Bhp from the Rootes/Chrysler engine than to get the same from a Ford engine. I shall describe the full works conversion.
This short piston combined with the long con rods gives you a 1922cc engine with flat top pistons just about flush with the top of the block. (In the standard engine the pistons do not come fully up to the top of the block.)
If a standard head is fitted the CR will be totally unusable (over 12:1), even the H120 Holbay head will give 11:1 CR which is far too high for road use (good for racing though). The Holbay head has a chamber volume of 43cc and the standard head a chamber volume of 38.6cc Either of these can be used but they must be ground out to a volume of approximately 50cc to stand a chance of running on four-star petrol.
Obviously only fairly new heads which have not been skimmed can be altered to this degree. It is also possible to fit even bigger pistons using this method but any thing bigger would require special head gaskets and some other modifications.