I highly doubt that either the 84mm stroke F20C crank or the 90.7mm stroke F22C crank will work in the F23 block, since those engines are so different from the rest of the H/F series. I'm not really sure what that gains you anyway - if you're trying to build a de-stroked F23 block, you might as well just skip the complicated hybrid setup and put your time and resources into fixing/replacing your H22 block.
If you decide to pursue the H22/F23 hybrid, you have a lot more homework ahead of you. Before you go any further though, here are a few things to consider:
- Using the F23 block limits you to using the F23 crank and F23-compatible rods (You may also be able to use F20B internals, but you'll need to do the homework). Note that stock F23 rods may not be safe to rev past 7000rpm, and there are very few aftermarket options.
- The F23 block doesn't HAVE to be bored out to 87mm (mine isn't), but either way, you'll have to figure out what to do about pistons. At 86mm, you could use the F23 pistons (giving you low compression, not recommended for N/A builds) or K20A2 pistons (giving you fairly high compression, not recommended if you want to boost it). If you bore to 87mm, you'll probably have to use custom-made pistons, as there may not be any ready-made 87mm pistons that fit on F23 rods.
- You'll have to use a standalone EMS, and either learn to tune the car yourself, or pay someone else to do it.
I've done this build myself (H22A1 head, K20A2 pistons, F23A1 block), and I don't recommend trying it unless you REALLY want the experience. In my opinion, this isn't a particularly cost-effective or reliable project to tackle.