rust repair tips

[75steelers]

Hey Guys I am new too this board and too restoring old trucks but is something I have always wanted to do. I figure I have found the experts. I just bought a 1970 gmc. May be someone can tell me what kind of deal I got if I got one. I payed $350.00 dollars for it. It has a 292 inline that cranks and runs beatifully I am in the process of repalcing the tranny. The question I have is their is a lot of underbody rust. the frame is good but the floorboard has good size holes in it and the panels around it I was looking at ricks store do those rocker panels and stuff bolt on or do you have to weld them. also the floor pans. any help would ber appreciated. I will put some pics on tomorrow so it can be seen