5.0 into 83 mustang V6 Convertible HELP

I picked up an 83 stang convertible with a 3.8 after finding out the heads were not only warped but cracked I decided to swap in a v8 from my friends 81 or 82 3/4 ton van. I rebuilt the motor then found out the oil pan didn't clear the frame so I am in the process of switching that and putting a cheapo chrome after market dipstick in it, but what I wanted to know is what else do I need for the swap. I picked up a double hump cross member, the factory c4 was rebuilt before i got the car, I have an 85 ho aluminum intake and a 4 barrel Holley. The motor mounts I got from AutoZone dont look right they are from an 83 v8 but the stud coming out of them is thicker then the original 3.8 mounts and also there is a little bump on them the one on the passenger side is slightly higher then the original and the drivers side is in the wrong spot all together. I can put up pictures is it would help. Should I drill the frame to match these or is there a better mount to use I don't really trust Autozone. I also found stock shorty headers do they fit the frame I was told they were from an 85 because they has no o2 sensor mounts. Do I need anything else? is there something I should change or modify ? Ive done motor swaps before so don't be afraid to be technical this is my first ford and first fox body so I just need advice.
Thanks
Anthony

The K member looks ok its more the mounts and stuff Im worried about I will take some pics tonight to show you guys what I am talking about.

I had to shrink the pictures ridiculously to get them on here but heres the passenger side mount I put the 6 cylinder next to the v8, and the oil pan I have and the headers. Are these right, the little nub that sticks up on the mount where it meets the k member is off by about an 1/8 to 1/4 of an inch also the diameter of the bolt is thicker.

This is the drivers side mount the stud is also thicker and this time the nub is in a completely different location its at like a 3 o clock as opposed to 9, should I just mark these and redrill the holes also should I be grinding the k member so the larger studs will fit? The hole they sit in is shaped like an upside down tear drop, should I open it up a little so the motor can sit lower?