I have the intention to try doing so with my 813 rig
I have the same intention.....Use my stable 221 as a VFO, run it through a 6AG7 - 6AG7 - 2E26 amp string for a 5-10 watt exciter.
The only holdup after 8 years of trying to build the 813 rig is finding suitable modulation irons.
Steve,
KK7UV