6v6 amps can generally take 6l6s no problem. You'll get more clean headroom and a slight volume increase. Note to all: the other way around does not work. 6v6s should NOT be loaded into 6l6 amps.
BD, go to www.eurotubes.com. Tell Bob what you have and what you're trying to do. Bob is a great guy and he'll take the time to answer any question's you might have.