Iron:
Dynaco Z565 or modern copies for the OPTx
Dynaco St.70 power Iron, probably best to get a modern improved version.
One 10Hy power inductor for the L-C power supply. 500 mA unit from Hammond will be adequate.

Cascode 6BQ7 or 6BK7B for a diff amp cascode front like Merlin
100 uF/370vac cap like spec-ed for Guinevere for the PS cap.

It will probably be good for ~12 W or so. Probably just out of Class A bias, but that's OK. B+ will be ~300.

If somebody wants to build this, I'll loan a pair of the Z565's. Email me.
regards,
Douglas

Praise the Lord, and pass the 813's!