...and here's another opinion...
the weight issue is a non-issue. As mentioned, the flathead is about the same weight. Most transmissions will be heavier, but not much and in the center of the car. If you meant the car, they were around 3100 stock, so that isn't a factor either. If you are talking a truck V10, that IS heavier....

First, low buck. This will not be the best, and you will give up handling and braking. Not the best way to go with that much power. Stock, low buck clip or IFS kit. You will have to do something major in back too.

Second, mid-range. Go with a Dakota swap and upgrade the brakes and springs at both ends. A step up, but still leaving some stuff on the table. There is a guy here that is finalizing a V10 Dakota. Talk to him about what's required.

Third, big buck. A custom built frame with HP stuff on all 4 corners. You might look into what a totalled viper donor would cost, and if the suspension and brakes could be incorporated. I know that the wheelbase/drivetrain/driver position will not allow dropping the '40 body on the viper chassis. You will not be able to build it to equal a viper's performance due to weight and center of gravity, but it will be the most balanced car this way.