Hello I will answer your question,

The short answer is yes the instrument panel does get removed to replace the heater core in a B2300. If you have the year I can provide specific information on how to do this and to replace the heater core

The optional information did not show up until just now. Sorry for making you state it twice the webmaster keeps promising to fix this bug but no joy yet.

To remove the dash:

Image Legend:

1. Center finish panel
2. Steering column opening cover
3. Steering column opening reinforcement
4. Cluster finish panel
5. Instrument cluster
6. Ash receptacle
7. Passenger air bag deactivation (PAD) switch (if equipped)
8. Glove compartment
9. Passenger side air bag module (if equipped)
10. Dashboard

Removal and Installation

1. Disconnect the negative battery cable.
2. Remove in the order shown in the figure, referring to Removal Notes.
3. Install in the reverse order of removal, referring to Installation Notes.

Removal Notes

Steering Column Opening Cover:
Remove two screws and pull cover straight out to release clips.

Dashboard:

1. Remove power distribution box from bracket and move aside.
2. Disconnect three gang bulkhead connectors in engine compartment next to vacuum booster

To remove the heater core:

Remove the plenum chamber

Remove the screws and remove the heater core cover

To remove the heater case you will have to discharge the AC system and remove the evaporator case as there are nuts for the heater case behind it

If this is the information you asked for please ACCEPT this answer. If not please ask

Thank you