just wondering if anyone knows if verada KJ tail-lights will fit onto a 98 TF magna?

Yes, with a boot lid swap. You will need either a TJ or KJ boot lid. Check my ride for reference. It is a 00 TH with a KJ boot/tail conversion.

so with this change over, does the kj boot just bolt on as a swap with the stock tf one or are there mods that need to be made to get it to fit?

It's a straight swap, You may need to rewire the new boots reverse lights.

It's a straight swap, You may need to rewire the new boots reverse lights......and you need to change the key/lock set up some how

can u just swap out the barrels or are they a different size? i got the mongoose m80g alarm anyway so i can pop the boot with the remote if get the shop to rewire the sensor