1994 was the last year for the older GM/Chrysler oddball size Din-1/2. In 1995 and for 1996 the Roadmaster was updated with an complete new sound system and got a true Double-Din radio.
For your '94 you can go salvage-yarding and pull a '95-96 Dash bezel, but you also need the inner plastic "cage" structure behind it for the larger stereo.
The only other issue...that nobody seems to have cured, is that the dimmer for your climate control runs through the stock Delco radio. With an aftermarket radio, the digital readout on your climate control will no longer dim, and those green numbers are BRIGHT at night. Something to be aware of...