The Linux PC-radio is not designed for VHF weak signal only. It is very flexible and designed to accomodate routines for all radio communication modes on all frequency bands. A good noise blanker may improve station performance a great deal. It is a good idea to have several noise blankers inserted at different points along the Rx signal path. Look here for hints on Noise blankers Power Amplifiers To be successful in two way DX communication, you need a good power amplifier.
Vacuum tubes are still the natural choice for high power.
As amateurs, we often use surplus tubes. They may be brand new, but if they have been stored for many years, they should be reconditioned before use. The vacuum is gradually deteriorating over time if a tube is left on the shelf. Here is a procedure to recondition power tubes that may decrease the risk of arcing due to poor vacuum. To my knowledge, few amateurs run their power amplifiers in class C because class C amplifier is far from linear and can not be used for amplification of SSB signals.