I have a friend that has one in a 79 ford bronco. I am amazed at how much torque it will produce and still rev to 6500 with a stock cam and valve springs. In order to make it a 428 you will have to bore it .080 to get to the standard 4.13 428 bore. If it will go that far why not. The thing to remember is they only made the merc 410 for two years if my memory is correct. If you are going to race it you will only have a small usage time out of it and then you can't rebuild it. So it might be better to leave it as a 410 and slowly bore it so you can continuely use it rebuild after rebuild. With a decent set of heads and a nice cam, I don't think you will be disappointed!

Dave