I do not have FAM for your year truck but I would research and find the cab to frame dimensions and verify that the cab floor to frame relationship is correct ( height of cab floor to frame near each of the cab mounts ). Not knowing if the "new frame" has been tweaked in its previous life and if you have the radiator support setting on the frame ( no pads , no shims ) then you'll need to work with the cab mounts. Just an opinion based on my experiences with a 54 1st series.
