better shoes for front drum brakes?

[willy]

I have a 1968 Charger R/T with 4 wheel drum brakes. I have been trying to get it to stop better without changing to disc brakes. I purchased some R4-S porterfield brake shoes and when I adjust them out to where they just start to touch they grab and lock up. I took them to a brake shop and had them ground to fit the new drums and that didn't help. They just seem to have way too much grip. I dont know what else to try. The stock shoes don't do this so it has to be something with the shoes. I would be willing to try Muscle Car Brakes if they are better but their shoes have a higher coificient of friction than the porterfield shoes. Does anyone have a good recomendation or heard of this problem befor? I have all new wheel cylinders, springs and drums.
Thanks,
Willy