This guide will let you know how to get 60/60 Heat mods in Warframe.
60/60 heat mods drop from various spy missions on certain planets, and the first two, Thermite rounds and Scorch, can drop as a C rotation reward from the kuva fortress spy missions.
You can bring just about any frame you want, though it is recommended to bring the ones that can avoid laser doors, teleport, or can resist getting knocked down, rhino, limbo, nova, ash, etc.
To get the C rotation rewards, you need to ensure you get all 5 data vaults; it might take you a few runs before the mod drops for you.
The next 60/60 heat mod is the volcanic edge, and it can drop as a c rotation reward from tier 1 spy missions.