Looking to buy/build 500-600 fwhp 360

I run a 360 with KB107 pistons. Did not rebalance! Has been this way for the last 11 years. Have run it hard and has kept together just fine. Every person that has rode in it thinks it's been balanced since it runs smooth. Runs the 292 mopar purple cam which likes rpm's. 3.91's out back too.