Converting 8 lug to 5 lug - '68 GMC 2500

[Giorgio]

'68 GMC 2500 - what would it take to convert 16 in. 8 lug rims to 15 in. 5 lug rims? Truck has been lowered with 3'' drop springs in front and 2'' rear shackles. Does not have disk brakes. Looking to find 15x8 rally wheels to replace 8 lugs. The existing rims have caps, chrome lugs and beauty rims. Tires are 245x75R16. Thanks

[Xeen]

The easiest route is to find a 1971-72 front suspension crossmember and take the whole smash, suspension, steering and brakes.
You will also want the brake power assist with bracket, master cylinder assembly including all brackets and rod with adjuster at pedal, as well as the prop valve.
If it is a 1972 you will also want the rear intermediate crossmember to route your rear brake line.
It is questionable that the front end will align with a 3" drop spring, some guys claim it can be done but the general rule of thumb is a 2" drop spring is max while retaining tension on the control arm durring full extension.