A couple more notes. These came in two slightly different power ratings, 500w @ 2 ohms for the earlier and 550w for the later builds. They were nice and put the output rating on the back of the case near the power cord.
If it has the original 12AX7 an EHX or JJ might make the tube pre sound even better and might give more life to your G+L. These came with a generic Chinese tube because of when they were made. I liked it with the original but A/B'd mine with a base model EHX and a JJ I had kicking around and the ehx won between the three, more noticeable with passives. Definitely worth doing some tube rolling with these.