I see you've already done this, but the radial tires and O.D. are the top 2 on my list. I've also added dual exhaust, HEI, new shocks, a full gauge instrument panel, and dynomat to the floor. Next will be front disc brakes and rear drum rebuild, complete suspension rebuild (stock) and finally the addition of my 261 stroker. I will also be replacing the bed and cab mounts.