(2)450 DP's vs (2)750 DP's

Your tuning approach looks good. Those 450’s I believe flow even less then what they are rated at. IMO those are a bit small for a 440. I think a 600-650 range carb would be more appropriate. 750’s could be a tad on the large size given the combo is very mild. I personally like to keep the MAB smaller and adjust around that.