Through the haze of time, I can somehow remember seeing the Allmans about 3 times. I know I remember Berry Oakley with an arc of what had to be Orion cabs (vertical vane looking stripes on speaker grill) on stage for two sets at the Atlanta Pop Festival in July of 1970. Does that work for that timeline? Both times that summer, Duane and Dickie played through Marshall stacks.
At one Florida festival called Winters End, I believe, Dickie Betts handed his guitar to Johnnie Winter, mid song, and he and Duane Allman tore it up on slide. It was absolutely large! I just remember Oakley with lots and lots of Sunn and Marshall for the leads. I may have seen the Kustom stuff, but know I remember the Sunn/Marshall connection from 1970. Southern rock never had it so good.....