I just finished putting a 5F1 Champ into a busted Champion 600 reissue, using a kit from Dave at Boothill Amps. It's a huge success; sounds great, dead quiet idling, pretty easy to do. It uses the old transformers and switch, which saves money, but that's all that's original. I wanted to put a Champ in there, and found out about his conversion kit while googling - it's on this site somewhere. His website shows full kits but doesn't mention this conversion - just ask for it! As far as I understand it, the preamp is on that board with it's own ground to the chassis, and the power section comes pre-assembled and attaches to the transformer ground. I went a bit crazy on extras - I added a Princeton-style tone control with a rotary pot switch to turn it off. I added a switch that lets me choose between 2 negative feedback resistors or off, and I did the same thing adding 2 different capacitors for a bright switch. There's also an 8" Weber speaker in there, which caused the only problem - the back of the chassis touches the top edge of the speaker and causes a terrible noise; it took me a few minutes to figure that out... I wrapped insulation tape over the back edge of the chassis and that fixed it.