This has been on my radar for nearly 10 years.
It's a complicated set of connections, which still has 'moving parts missing'.
What i can share is:
I can tell you that Monster Masters were at 6087 Sunset Blvd. And that it was a John D. Imus (you can find john D. easily on Discogs) Fred Imus and George Russell. George was at 7408 Fountain Ave (as too was Gold Cup Music Company, Gretchen Christopher (who can easily be found on Discogs). Tourist Records was also at 6087 Sunset. Run by Castle Newell & Lewis Finston.
Take 6 was at 6565 Sunset. A big building.(see 1966 PIC).
The 'moving parts' that i still revisit include-Tank Jernigan,Colonel Splendid (The Emporer DJ), Jimmy Gresham, Sarah & The Sanctified Six...to name just a few.
Hope it helps.
P.S. Larry Johnson (William L Johnson) is likely the head honcho of Vendo Music pubbery.