Bob: Your question sounds simple to answer but it isn't. First, how long is the outboard track? I would probably duplicate that length (provided it has worked for you - read on to see what I'm talking about) unless the track is a mile long. I would think a lenght of 5' would do nicely.That being said, you may require a little more length than normal because you are trying to work with 3 different sails. So what is normal for a given sail? To get it exactly right you would have to trim the jib through the whole range of wind speed by checking the break of the sail. In other words, you know the fairlead position is correct when you come almost head to wind and the sail breaks evenly from top to bottom. That is too much work for this exercise but hopefully that is the proccedure you use to set your fairlead positon when your sailing. If you went through that process you have an idea as to if your outboard length is in the ball park.As far as positioning the track, I would get as close to the cabin/deck curviture that I could but you don't want the fairlead block so close that it is banging into the side of the cabin. If it is not possable to follow the curviture, straight would be OK. Try to follow the curviture of the outboard track but anything is better, when sailing closehauled, than just using the outboard track. I almost think I could write 3 pages on this subject. I used to race on a Newport 30 and the skipper decided to install a 3' inboard track. He never bothered asking me about it and really he was under no obligation to do so. One Wed night I showed up for a race and he said you'll never guess what I've added - 3' inboard tracks. I thought great but what happened was we had plenty of front track but not enough back track space. The end result is we had to move it back and he was left with 3 nice looking extra holes in the deck on each side. That is why I said at the outset, this placement is not easy when your trying to work with a short track but a long 8'track is just overkill.My C30 has a short cabin top inboard track. It would work for a 135 but not a 155 or a 100. Sadly, I could not get it to work for any sail because I could never figure out how to get around the problem of the safty lines being in the way.I really don't feel I've adequately answered your question but hope I've given you some stuff to think about. Maybe another lister can chime in.