You have to get the linkages worked out first.
The 2bbl and the 4bbl top linkages to the firewall are different, both the cable anchor and the top linkrod. The governors are/may also be calibrated differently, but again the governor pressure is modified by the TV pressure which is controlled by the KD linkage.
So to find out what is going on remove the top linkrod completely;put it on the workbench.
Next make sure the throttle plates are opening completely. With the engine off,Have a helper inside the car floor the gaspedal, while you, under the hood, shine a light down the holes and make sure the primaries are standing WOT, that is to say , open as far as they go.If they are not WOT, then figure out how, and make it happen. This is somewhat paramount. The KD pin cannot properly send the right information to the VB(valvebody), until this is correct. Furthermore that KD pin needs to be in the correct position, relative to the throttle shaft, to properly time the TV pressure and KD events.
Finally, get under the car and tie the TV lever to the back, as far as it will go. When you begin this process, the first say 40% of it's travel nothing may be happening, but soon you will feel the internal resistance as the TV spring,inside, engages.You must feel this springiness before you proceed. The TV lever should be at about 90* to the vehicle centerline,at this point, perhaps a little less. So pump the lever(you cannot hurt anything inside), and feel that spring. If you feel it and it pushes the lever back, then continue. OK so push it as far back as iot goes and anchor it there. You can zip-tie it or wire it some such a thing.
Next take it for a spin with the top linkrod still on the bench.
With the lever tied all the way back, the shifts will all be harsh, and all should be very delayed. Depending on the internal calibrationS, it could shift well after 4000 and even 5000. So if it won't go into second by some safe-for-your-engine, don't push it. Go back to the shop and reposition the lever allowing about a half inch slack this time, and retest.
Having done this, you have figured learned a bit about what the governor pressure to TV pressure relationship is, and if it is possible to make your current parts work.
When this has been discovered, cut the cable-tie and reinstall the top linkrod.Now fix what needs fixing.
In all likelihood the cable-anchor will need to be relocated further forward to properly open the throttles.Then the KD pin will need to be verified to be in the correct location. And finally the linkrod will need to be stretched to make the TV function correctly.
Or you can just buy the proper parts; but in NZ that might be easier said than done. These mods have been documented here on FABO, so a little time spent searching should bring some stuff up.
Oh, almost forgot;
Once everything is in proper working relationship, and the upshifts are still too early, come on back, we'll talk about messing with the pressures