Now that you've sourced the crank and cylinder head for your build, the next challenge is finding suitable pistons that will give you an increase in static compression over the standard 1580 pistons... which you can buy almost anywhere (1580 8v might even be a current production engine in some countries)
I've found that a Mahle 0872 works. Trouble is I bought up on them a few years back and probably have the bulk of the worlds supply, not kidding, I had about 15 sets at one stage...down to maybe 10 now.
I have very limited oversizes though, as I bought them all for my racing programme...and 86.8 is the size that suited my needs best, as I end up with 1598cc , under the 1600cc capacity limit of the class I'm building for.
I have a bit of a write up on 1600's here if you haven't seen it already
http://www.turbo124.com/forum/viewtopic.php?f=10&t=7402
So I honestly only have 86.8 and 87.0 sizes in this piston type ...the 86.8's I'm hanging onto for my under 1600 engines...
87.0 is a particularly nice size though, as total seal rings are available in 86.0, 86.5 and yep 87.0 ... so it opens up nice ring options... and your at 1602 cc's
Another workable option would be having pistons made, and this would open up more ring options... and let you get whatever piston size you wanted.
The 1580 standard ring pack is a nice option, thinner rings, (1.5/1.75/3 whereas standard is 1.5/2/4) and even a moly coated options from the factory...
Matt at midwest has Wieseco pistons made with an increased compression height and (handed) flycuts to suit oversized inlet valves, wouldn't be too hard to copy his design exactly, but drop the CH down to maybe 33.5mm ...run it past him as I think he could sell a few sets given all the interest in stroking to 1600.
Only downside is your talking around the $800 (maybe plus) dollar mark though for a set of custom pistons and rings .. that's pushing close to double what a set of cast pistons would cost you at around the $500 mark... your choice though as it's your money and your build.
SteveC