Looks like a K block - 63mm mains, rear thrust, not pre-equipped for piston oil squirters - from a 740, given the RH engine mount in the pic.
You will see a "K" cast into the block on the LH side (inlet side), in the general area of the knock sensor.
e.g., in white circle:
K blocks were used from about 1988 until 1991, when it was replaced with the L block. The L blocks from 1993 on (with round toothed timing gears) were either equipped with oil squirters, or pre-drilled for them.
Depending on your K block's manufacture date, it may have 8mm conrods. 13mm conrods are a direct swap (same big end bearing size).
I recently ordered a set of first oversize B230F NA pistons and rings from Skandix, after CVI informed me they didn't expect any new stock from their supplier until June. You may have better luck with B230FT pistons.
All rear main B230 blocks use the same big end and main bearing kits. B21 / B23 and centre thrust B230 blocks use different bearings. Timing belts for K blocks are generally square toothed, and not the Penta type.
530 heads from K blocks are often fitted with the small (early) type of valve springs. FCP offer a kit (p/n 271793 with the new medium spring (p/n 9135130), plus suitable upper and lower retainer washers, for about $11.19 USD per kit (8 needed). Just checked - they're a bit cheaper now. Note the 531 heads have different springs and washers/retainers, but both heads use the same keepers.
For my Project GoaT engine, I'm using genuine seals for the rear main, the front crank seal, the aux shaft seal, and the oil pump 'O' rings (which AFAIC are critical), and either Continental or the Victor Reinz kit for the other gaskets and seals. Gasket kits for the centre thrust and rear thrust engines are the same, AFAIK.
The Oz Volvo Tech Archive has the Green Book for reconditioning the B230 engines, where torque settings, measurements, etc may be found.
