carb. crazzzzyness!!!!!!!!!

As for a new carb, for the easiest replacement, my choice would be the 770/870 Holley Avenger. If going Eddy, which would require some fuel line/ linkage fiddling, i would use the 800 Thunder series.

With that said, it's possible to make the 650DP usable for your situation, but will require tuning as 65val referred to. And it's not to say that a new replacement wont need a little tweaking itself.