How to design and build RF amplifier, that work in 450Khz
Since 455 kHz was commonly used for intermediate frequency (IF) amplifiers for AM medium-wave receivers, there are many schematics available, such as this from Pan-Tex,



Or this from Next.Gr,



The output from either should be sufficient for short-range communication. Since a practical (and legal) antenna at this frequency is a small fraction of the wavelength, a sensitive and selective receiver is needed. Ceramic resonators give a sharp pass-band and might help in place of IF transformers.

That said, this is a busy frequency, and expect that there will be interference from MW radio oscillators and other devices.