Six years on, Chris DL1CR pointed me to this thread. Below is my 28 and 144MHz homebrew transceiver project from around 2021 (lockdown project).
Because I built the exciter I had the opportunity to take RF drive before the PA. So I didnt need to use much attenuation.
My transverter (and the homebrew 28MHz SSB monoband transceiver) performed well (although the TCXO mod would have addressed a few hundred Hz drift on switch-on) and I discovered what a great band 2m SSB is for hilltop portable work. Always someone monitoring 144.1 SSB.
SP-8: a homebrew 28MHz SSB transceiver for a UR3LMZ 144MHz transverter | VK3HN