1966 c20 8 lug to 6 lug swap. what front parts and coil rear end is bolt in

[inkfamous13]

Looking for help to swap out this 8 lug set up to 6 lug. This 66 c20 has front and rear coils, 283,nv-540 (go) 5 spd. Geared way to low. Would swaping rear end fix the low gear problems? Or would swaping out trans be better? Its a dealer installed 5spd so id like to keep it. What front end parts will blot up easy. Would lower arms, spindles, tie rods & center link, brakes from a 63-66 c10 bolt up? Or would i need whole crossmember? Or would i be better off going 67-70 c10? Not looking to do disk brakes. Also what power brake booster is bolt on? So any answers or help or leads on parts for sale to do this is greatly appreciated. Thanks.