Bob C said:
I would put in the IFS. It's much easier and it looks a lot better and you don't need to fab .
Bob
I guess this depends on the look you are trying to obtain. Some people want to achieve a "factory" appearance on a frame. The IFS from the 79-81 Cutlass/Malibu when mated together through notching (as described in the earlier post) actually looks like the fame belongs there.
A Fatman IFS is clean in appearance for that section of the frame, but the mating of the sub frame and the 46 Chevy frame generally requires reinforcing plates at the mating point (which almost always looks like it was added).
As for a radiator support or bumper brackets, you can reuse the 46 Chevy bumper brackets and radiator support. The bumper brackets actually line up with the metal of the sub frame. All I had to do with my Oldsmobile is to make mounting holes on the frame to bolt the bumper brackets and the radiator support on.
Using original parts would allow you to obtain a factory type look, but you know how you want your vehicle. Although both methods are relatively easy, you choose what best suits you.
Best of luck,
~Joe