That's what I'm running right now, 1984 B23 block with a 1993 530 head. Just get the conversion gasket set for a B23 which is all the gaskets for the bottom end and you'll have to order a late model valve cover gasket separately. You may need a square tooth cam gear if the head is from a car with a round tooth timing belt. I think everything else bolts up. Mine is not stock though, I had the head ported and 2mm larger valves installed. I also have an adjustable cam gear. It's put together with ARP head studs. I put all new bearings in, nos B23 turbo pistons. The B23 is one of the stouter redblocks, it also has a flat plane crank. Also new oil pump. It's a rabbit hole once you start tinkering.