Your options with the standard block are "2.0L" (standard 88mm crank), "2.3L" (100mm crank) or one of the custom crank "2.2L" (92/94mm crank) or "2.4L" (102mm+ crank) engines. The 2.2L kits will not be cheap, but the choice is out there. Unless you're dead set on blowing at least $3000 on a new stroker kit, a 2.3 is the simplest and most proven option.
The "2.3L" stroker can be built using a factory forged 4G64 crank and off the shelf parts (reuse stock or standard length rods and readily available stroker pistons), and is significantly less expensive as a result. With a used 100mm crank checked by a machine shop, your stock rods and stroker pistons, you can fill your block with spinning things for less than $600-700. (About $1000 if you go for aftermarket rods, and about $400 more will get you a new OEM forged/nitrided crank instead of a used one).
The maximum overbore you can run practically is 0.060" over (1.5mm). The 4G63 block is supposedly capable of between .080 and .088" of overbore before the cylinder walls start to get too thin, but anything over 0.060 is going to require custom slugs.
Unless you're building some kind of insane race-car, the gains to be had by overboring aren't really even noticable. As far as aftermarket stroker kits, You're better off putting the money towards a good turbo and intercooler, or a built transmission to handle the torque from the stroker. I don't know about you, but unless I had gobs and gobs of cash to burn and really really wanted a 2.2L kit, I can think of much better things to do with $2000.
