Story complete:
I ordered the Dakota radiator bushings from Summit. They are larger in all dimensions except flange thickness. I was particularly worried that they would not pass thru the shim holes, but with some silicone grease they worked fine, without a mm to spare.
The radiator studs are way smaller than the new bushing voids, so I bought an assortment of vacuum caps for $7 to make up the difference. I put a short sleeve of heat shrink on the stud, then slid a red cap over for a nice, snug fit. The black caps filled the bushings perfectly, but the red caps held them off the tank bottom a few mm, so I snipped the ends off and they were perfect. I greased them well so they would easily stab into the black cups. The OE's stay on the radiator to drop thru the shims, but with the OD difference, I pushed the new ones in first and then installed the radiator. All totaled, I spent about $40 on the project in direct parts.
I would recommend taking the jumper hose from the passenger side radiator steam nip ple completely off before starting. It was a constant pain coming out and going back in with the radiator. I also bought a gravity feed/bleed bucket setup after 30 years of Viper ownership. Much cleaner and more efficient purging trapped air as the t-stat opens and causes bubbles to belch and coolant replenishes.
