1/48 HobbyBoss F-84F

Hello everyone! just started modeling and completed a couple 1/72 scales and moved on to 1/48. I have a few Questions about the F-84F and a lot of what I have read confirms what I've encountered except no explanation on how to solve the issues. I'm currently at the stage of buttoning up the fuselage and as describe, the intake cone does not fit into the space where it is supposed to. not even remotely. I have plenty of sand paper, where do I start and do I sand the notches on the fuselage or sand the peice itself? I've dry fit the gear assembly and cone peice and tryed to put the two halves of the fuselage together to see how it would fit and it's not clear on how this going to work in the instructions. The other question is weight. I have strips of 7 gram flat weights with the sticky backs on them that I bought at my local hobby shop and it seems like they'll work fine but placement is the issue. it appears I can stick a few under the cockpit assembly but don't know if that's to far back or not Or how much weight I'm actually going to need all together? the nose gear is flimsy but I think it will be fine as long as it's not to heavy but I don't want to push the envelope. any advice is welcomed.