Advice on stroker build with cracked cylinder

The Melling sleeves catalog says this: "A long crack or large chunk missing will reduce the press because the damage will open under stress. Increase or decrease the amount of press according to what will seal the damage. Pressure testing is recommended." (The term 'press' in this context means the amount of interference fit.) So this seems like a common situation. The sleeve itself contains the cylinder pressure and the good ones are made from a high quality ductile iron material; the residual block material is there to hold it in place. If the rest of the block in that bore is good and not cracked to up near the deck or the bottom of the bore, then the sleeve should be secure.

Bursting pressure of a .093" sleeve should be well over 2000 psi. So it will contain your cylinder pressures just fine. (And you can get .125" thick walled ones for more strength.) That is as strong or stronger than plain cast iron bores once the core shifts are considered. I can't address the side thrust on the sleeve in computed numbers, but all sleeves have to support thrust forces by themselves so it indeed does look to be OK, even with the crack. Being made of ductile iron achieves this.

The area with the crack may not create any interference pressure to hold the sleeve, as it will spread. So it all has to be held by the top and bottom areas; wet-liner sleeved blocks work that way so it seems OK. Plus, I have to wonder how many bores have holes once bored for a sleeve anyway, and how many develop unseen cracks in the remaining cylinder wall material with the interference fit process.

I would try to stop drill the ends of those cracks to prevent the crack from spread up and down; perhaps some of the machinists will comment. My instinct would be to seal that crack while installing the sleeve to try to keep coolant from creeping around in between the sleeve and block. That could create corrosion and some future issues. It may be that the compounds used for sleeve retention do this.

And Melling lists some high performance sleeves that can be considerably overbored in the future.
https://www.melling.com/wp-content/uploads/2018/06/Melling-2018-Cylinder-Sleeve-Catalog.pdf

BTW, I would have the block examined thoroughly before moving ahead.

All in all, I would do it and not be worried. I have done a few unconventional mods to heads and blocks in the past and they all worked out. Sleeving is well known process so seems like a pretty good bet here.