Well,, looks like no one's gonna believe me without pictures, so here's pictures.
First, a side by side with the Monogram 1/24 '69 dash in red and the MPC 1/25 dash in white,,
Here's the Monogram 1/24 dash in the MPC 1/25 interior,, Pretty poor fit, yes?
, , , and the MPC in [on?] the Monogram bucket,,,
Looks like it will fit well if you trim the mounting tabs off the side, maybe?
BTW, bonus image of the CORRECT '68 GTO seat and door panel trim pattern.