ramrod I think the importance about conrods and their strength or lack of is based more on revs than horsepower
With a turbo engine, it's about resilience to detonation.
Detonation + 9mm rods means you will kill the engine; detonation + 13mm rods means you probably might. Even so, NA 240s in the US had 9mm rod failures, and so 9mm rods were superseded with 13mm rods and given the same part number. The 'low friction' adventure was a design flaw.
If the OP is building a track 740, the fact that a B23 was never certified for ULP in OZ isn't going to bother any roadworthy inspection engineer. The B23's forged crank and M rods are plenty strong. But the road rulebook basically says you can't swap in an older engine into a post-ULP car - and 'engine' as far as they're concerned means 'block', since the block has the ID numbers on it.
For a road car, the OP is better off getting a late L-block B230 and building that up, and fitting a good wideband sensor system to it. NA L-blocks are more available and less worn, and are the same as +t L-blocks once you drill holes for the turbo oil feed and drain. OE Mahle turbo slugs and rings are still available.
Adding wideband sensors should be a priority too.