You cant run a mech IP & 4L80 trans through the stock PCM and get it to shift correctly no TPS this vintage vehicle, that is a function of optic sensor in IP-vs crank sens-vs APP feedback-vs trans feedback-vs PCM.

You will have to run the stand alone puter to get it to shift correctly.

Also you will need to put a lift pump to supply the IP is you want to maintaing fuel to work the engine at load.

There is a member on thetruckstop.us that wrote one of the best conversion references yet, how to convert the DS4 to DB2 he used to sell it on ebay I just looked but I did not find it his name is Bobbie Martin