crossmember swappers inside please

[Wilson!]

i have a '65 GMC that i'm looking to swap to power disc and power steering. i have the complete crossmemeber including control arms, spindles, wheels, springs, sway bar, brake lines, prop valve, steering gear, idler arm, EVERYTHING from the front from a '79 GMC C15.
i plan on putting lowered spindles and springs for the '79 on the truck at the same time as doing the disc brake and power steering swap.
is there an actual advantage to using the later crossmember? the engine is still in my truck, and to me it looks like it would be easier to just swap the upper and lower arms while i have everything apart doing the spindles and springs than swapping the crossmember while the engine is still in the truck. is the crossmember swap easier when your just swapping straight over?