OOOH, this is weird- not mine -factory 360 Valiant 4D !!!

YY1 said
...and here's yet another extenuating circumstance or never say never...

Did they ever put a HP motor in a Valiant?

No... except a 1970 Valiant Duster 340, and a 76 Valiant 4D police car!

As far as I remember You could order the 273 c.i. Commando for all Valiants (with the exception of Stations) in 1966.