Amp Head trades

[NCI]

Hola, I've been searching for sometime on craigslist and stumbled across a 100 watt H&k duotone head. Curious as to how much the seller was willing to let it go, I emailed him with an offer of an Orange rocker 30 head or a 1968 j-50 Gibson. He said he would take into consideration the Rocker with some cash. Would you think this is a fair trade? What's the main difference between these amp heads? Thanks.

Feel free to post any other amp tradings here.