440 duster. Need engine build advice

I had a cast crank/rod 440 internally balanced with the +7cc Speed Pro forged pistons (flat top with valve reliefs) - you can get a harmonic balancer specific to this application from Summit for about 80 or 90 bucks. I still have the factory torque converter behind it and it feels like it may have a little more vibration but doesn't feel excessive, and I might be feeling more of that because I have "custom" solid engine mounts, all steel with no bushing. Eventually I will be looking for about a 2500 stall convertor that will be zero balanced, but it's not in the budget right now.