I recently purchased a 67 BF Super Reverb for half that. No JBL's, but everything else about it is more valuable than a 75 Silverface, especially one that needs a cap job and who knows what else.
The last SF Twin with JBL's that I bought was $750 but that was pre-pandemic. These days, I would guess maybe $1200 is a reasonable price, but even that is starting to come back down. There isn't that big of a market for heavy 80+ watt amps. Mostly just us older guys who grew up on big iron, and many of us are downsizing as backs and joints age.
BTW, 1975 D-120 F's are physically K-120's with the old Fender designation. That's actually a plus for most people on this forum as that would be what Jerry and the dead were using through most of the 70's+, either new or reconed, at least until they switched to the E's and cones in the 80's.
