The speedometer cable had to bend fairly sharply before, to get around the brake booster, so now that the driven gear housing is sticking out quite a bit further, the speedo cable has to kink even more. One solution would be to mount a corner drive in the speedo cable. It just so happens that I bought two of those angle-drives at the big swap-meet. One of them was for a big truck, so not for this application, but the other was pretty good except for one mounting position, [where you should screw on the cable nut]. The seller had lathed down the male threads and mounted a brass bushing on that end. It didn't work for him and it certainly wouldn't work for me. I robbed the male threads out of another old speedo drive and made it fit this corner drive and pressed it together. [pic one]
[pic two] is the corner drive installed.
[pic three] is most of the truck put back together, like the crossmember, exhaust and driveshaft.