There is someone who used a ca20 bottom end, ca18 main ladder brace with mitsu rods, ca20 crank, 6800rpm redline with ca18det top end was doing lap times as fast as his sr20det upgrade. He limited it to 6800rpm using stock ca20 cast crank but apparantely had more midrange than the sr20.
The ca20 block is taller so with longer rods and ca18de crank you can have very good rod stroke ratio. Have to upgrade all to ca18det but use longer conrods. The better rod stroke ratio, less side loading and bigger capacity should equate to a strong engine. Full counterweighed spool crank would help they come in ca18 or 20 strokes but if using a the ca20 stroke in a ca18 block I think you better get very shoort comp height pistons and longer rods than what spool supply as the rods stroke ratio is still not great in that combo.