My old full size Blazer had a 700R4 but I thought it was a NP241? It did have a chain from Dogde diesel and the Slip Yoke Eliminator with CV joint. But in that truck the VSS in behind the speedo...

If it's just an offroader there's no need for the TCC. For the offroading around here it's all slow rock crawling and although I had WOT tuned and TCC I never used it...

Not sure but if it were me I'd run the 4.3L injectors, if they are not enough add a adjustable regulator and bump up pressure. That's always worked for me.