DF1QE Yes, I also built these push pull oscillators ('Gegentakt') at very young age for FM with ECC85 etc. Output was ca. 5W.
Here (i.e. Hilversum region) called that oscillator a 'Kalitron' and we used 'Butterfly' capacitors from Philips army equipment.
About the injection of the LO. A friend of mine, who designed LNB's for Philips in the 80 - 90's told me about the symmetrical injection and its positive effect on phase noise in NXP (former Philips) (TFF) chips.
Based on this information and the fact I was donated a LNB with a NXP chipset I tried to convert my friends hint into a practical solution.
Glad that it's of use for/to you : -)