I bought a new kit for mine some years ago, and had to drill out the holes.
I no longer remember the sizes, but what you say sounds right. I used grade 8 bolts purchased at my local hardware store. I've put about 10,000 miles on the conversion with no problems.
I shimmed with some washers and had no trouble getting it right.
I've had 8 inch wheels on mine, and currently have 7 inch wheels on it. I've not had any rubbing problems.
Now the bad news, mine is an AD not a TF so my experience drilling holes, and buying bolts and spacers is similar, but with the different cab and frame I have no idea if my steering clearance means anything to you or not.
