They certainly aren't sleeved as stock, and I can't imagine someone doing it to salvage a busted block when you could always just get another block for very little money. Unless someone wanted a REALLY big bore B20?

I've had a couple of B20 blocks bored to B21 size, and I'm using one of those currently in my PV. Works great!

Std dimensions are:
B18 - 84.14 mm (84.64 and 84.89 mm std oversizes)
B20 - 88.9 mm (89.29 and 89.67 mm std oversizes)
B21 - 92 mm (92.5 and 93 mm std oversizes)
B23 - 96 mm (96.3 and 96.6 mm std oversizes)

Machine shops usually seem pretty skeptical about overboring a block 3 mm, but it works well on the thicker than normal Volvo block. I'd guess the 96mm B23 size is not possible, if you want more displacement in your pushrod Volvo engine than the ~ 2.2 liters the 92mm pistons provide then you should probably look to a stroker crank. KgTrimning lists stroker cranks that add ~200 cc's more for a 2.4 liter in combination with a big bore.