Hi Bill,
My '68 C/10 came from the factory with an L6 292, SM465, 3.73 12-bolt rear, and 7.00x17.5 tires.
I'm on my 3rd engine [first rebuild of original mill] I run a .030 bore, 260H Crane cam, Rhoads lifters, Offy intake, Edelbrock 500 CFM [AFB-clone]* and Clifford headers. I don't need carb heat in Tucson. Points ignition w/ Mallory Voltmaster coil (but have hi-end Pertronix on the shelf for later). Centerforce II clutch. Dual exhaust with crossover, turbo mufflers exiting behind rear tires. Tires are now Dunlop 235/85/R16LTs and I upgraded the rear end to an Eaton posi.
It's a street/work truck. You don't have to copy my set up, but may find the information useful.

* I used to have a Holley 390, but after 25 years -- I'm thru with Holleys!

[I didn't know you could still get a 292 crate motor?]

I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.