We want to put a 1992 Park Ave 3800 motor into a 1999 Pk AV 3800. Is that posssible

Go to Advanced Auto or similar parts store buy matinance book for your year Buick give all information on how to fix all most anything

I know the security antitheft feature will cause you problems after installation, but that is something that you can bypass.

http://vatspasslockpasskeysecurityhelp.yolasite.com/

U1300 - GMTypeNetwork - Manufacturer Controlled DTC - Manufacturer ControlledDescriptionClass 2 Circuit Short to Ground Conditions
CauseDTC B1327 not set as a current code, the ignition switch position requires serial data communication to occur, no valid messages were detected on the Class 2 serial data circuit, or the voltage level detected on the Class 2 serial data circuit is low for 3 seconds
short to ground or open wire in data circuit

Make a diagram of how the belt is on the motor,
then cut it off & move on to the next item you have to do

The code indicates the TPS is still bad and the code is usually right, but it could be a wiring issue at the TPS connector or less likely a computer issue.
To test the TPS circuit, you need to check voltage and ground from the ECM - 5v is the normal reading between the ECM reference circuit and the ECM ground circuit at the TPS connector. Checking the TPS signal circuit to the ECM requires monitoring the TPS signal on a scan tool while jumping the 5v reference and the signal circuits. The TPS reading should go from high when the circuit is jumpered to low when the jumper is removed.

The wire from the battery cable is the body ground. It should be connected to the inner fender on a bolt. As for the two broken wires, can you put them back together with sealed **** connectors.

what is the bracket called that mounts to the front of the motor and also to the wheel well

Do you have power at the injector plugs with the key on?

The L67 motor in the park ave ultras use a Eaton m90 supercharger. The coupler in the noise cone will go bad. Try replacing the coupler. Can usually purchase one for 40.00 from a shop that rebuilds them. Hope this helps.

I would seriously have a cat put back on you need that back pressure and have the O2 sensors replaced. Sounds like it may be time for a major tune up