I was quite happy with the generic red poly bushing kit from Summit. They are round, fit a bolt through. Another $20 in the correct size bolts and washers (grade 8) from Tractor Supply and you'll be set. The trouble I had trying to get cab and radiator bushings from manufacturers were that your truck, once sitting on an S10 chassis and your fabricated radiator mount will be pretty specific to your build. Better to get a one size fits all and use washers or spacers to help adjust the cab and core support so the sheet metal lines up perfectly.
https://www.summitracing.com/parts/ENS-9-9528R
