410 LA small block will not rev past 6000

You’re 20* short on the camshaft duration. I ran a [email protected] solid in a 365 with 4.30 5400 max power. Now a 244/[email protected] with 3.91 max power 5800 revs to 6200 slower ET. Your valve “dwell” is too rapid. I was going to order a 268/278 for a 414 and was advised to spec 272/282 for 6700 rpm. Look up Huges Dyno charts. He’s running high 260’s at .050 in 360’s with oem castings #587. Your motor is trying to breath through a restricted dwell window. You need about 4-6* more advance too.