Hello,
I am beginning a 440 stroker build. I'm going to use 440Source for the kit. Has anybody had bad luck with this company?

Also, what is the recommended method for balancing the crank; with or without the harmonic balancer and flex plate?

Regards

The rotating assembly should be neutral balanced , as should be your dampner and and flexplate , I would have the dampner and flexplate checked separately and corrected if needed. On a neutral balance rotating assembly you shouldn't need to have those parts installed .

Looks like you are in Detroit so there are lots of machine shops in the area that can handle the engine build for you including the balance work. Best bet is to go sit down with someone at the engine shop before you buy too many parts and see what they have to say.